Somewhere in the English countryside, a bushy-haired young man is taking a relaxing walk. It is Mike Yates -- recently drummed out of UNIT for betraying his superiors.

As he walks, the Doctor and the Brigadier are attending a show. A comedian with a thick accent is making bad jokes. The Brigadiers rolls his eyes at the Doctor, who looks embarrassed. The Brigadier comments to the Doctor that they are wasting their time. But when the announcer tells them the next act is an exotic dancer, his attention perks up.

Mike approaches a big country house. He walks in and hears some quiet chanting. Ever the operative, he sneaks down into the cellar to investigate.

He sees five men sitting around an ornate Mandela, chanting the lotus chant and banging cymbals. He watches in quiet fascination as the chanting grows louder and more frantic. A blue glow appears on the Mandela. Mike leans forward to get a better look but touches a spider web, making him jerk back. He knocks over a candle, which rolls loudly down the stairs. The men stop chanting and look around suspiciously but Mike has vanished.

The exotic Scheherazade has finished her act. The Doctor teases the Brigadier for his rapt attention; the Brigadier deflects it saying he should adapt some of her exercises for men. But before the Doctor can get in another quip, the next act is announced -- the mind-reader Professor Clegg. The Doctor eagerly sits up. This is what they came for.

The group of chanting men ask their middle-aged leader -- Lupton -- if they should try again but the mood is clearly lost. They think that it was only the wind that knocked down the candle until they hear a car drive off - the sports car belonging to their "new friend, Mr. Yates."

The next day, Clegg arrives at UNIT headquarters to met the Doctor. He thinks that the Brigadier wants him to perform his act for some regimental show. But the Doctor explains he is researching ESP and wants Clegg to help him.

Clegg is a little embarrassed and the Brigadier asks him if his act was all a trick. Clegg admits to this and the Doctor speculates he was using a word code with his assistant. Clegg asks him if the secret of his act is safe the Doctor assures him that it is: he will never tell anyone that Clegg is a powerful clairvoyant. Clegg is alarmed but the Doctor points out he made some mistakes the night before -- giving answers before his assistant had spoken a word.

Clegg collapses into a chair, lamenting that he doesn't want this new power. He was happier just doing his act. The Doctor is sympathetic, asking if there have been any other power such as psychokenesis - moving objects with his mind. Clegg nods and the Doctor asks the actor to demonstrate his powers.

Clegg reluctantly agrees and concentrates on a breakfast tray. To their astonishment, it rises and floats across the room. But Clegg can't keep it up and the tray falls to the ground with a clatter.

The amazed Brigadier suggest that should be used in his act but Clegg thinks he would lose his sanity doing it. The Doctor reassures him, explaining that his powers are normal -- they are just dormant in most humans. Clegg incredulously asks if the Doctor can figure out why he's different and the Time Lord agrees to help all he can.

Lupton speaks to a young monk named Cho-Je. He objects to the arrival of a female journalist but the Tibetan reassures him, explaining they can't just shut out the world. Lupton says that he came there for solitude but Cho-Je explains that he must learn to walk in solitude everywhere. Besides, Mike Yates has already left to pick her up.

At the station, Sarah Jane Smith meets Mike and they hop into his sports car. They roar off into the countryside as the pretty dark-haired journalist pushes the reluctant ex-soldier for an explanation.

Lupton explains to Barnes -- one of the men from the Mandela circle -- that of course it was Yates who was watching them. The men want to stop their experiments but Lupton insists they were on the verge of a breakthrough.

They are interrupted by the arrival of big lumbering man named Tommy. Tommy has the mind of a child -- he speaks simply and tries to show them a pretty flower. He then tries to drag them off to tea but they shove him to the ground, crushing the flower. He starts crying.

Sarah continues to taunt Mike, asking what he wants to show her. He fobs her off with a vague notion that she can write a story about the meditation center in the center of England. But her keen journalistic instincts are unsatisfied. She asks why he is there and he explains that he needed to sort himself out after the business with the dinosaurs. He saw an article about the Tibetan monks and decided to try it out.

In the basement, Lupton's men are once again chanting around the Mandela.

Mike has now told Sarah about the events of the previous night. She suggest that they are doing just doing some extra meditation, but Mike wonders why they would be so secretive about it. He thinks they are tapping some unholy power -- which would concern UNIT. With a laugh, Sarah realizes why he called her.

The chanting grows in power, Lupton's voice becoming fierce in concentration.

As Sarah agrees to act as a go-between with the Brigadier, they suddenly see a tractor in the middle of the road. Mike violently swerves to avoid it, then looks back to see an empty road. Sarah is now convinced something dangerous is going on.

The Doctor connects Clegg to a machine that monitors brainwaves. He asks the Brigadier for an object and the soldier hands him a pocket watch. As the Doctor watches an oscilloscope, Clegg contemplates the shiny object.

Clegg drifts out as he begins a psychic reading of the watch. It is 11 years old. Given to the Brigadier in a hotel by the sea in Brighton. From a young lady named Doris in appreciation for . . . but The Brigadier looks uncomfortable and grabs the watch back before more can be revealed. The Doctor taunts him that maybe too much has already been said.

The Doctor then connects Clegg to an IRIS machine that will make pictures from his thoughts. He hands him the sonic screwdriver. Drashigs appear on the monitor with scenes of the Doctor using the screwdriver to create explosions and drive them off.

Sarah has now arrived at the monastery and is interviewing Cho-Je. He explains that he wants men to face their fears and find their true self. He will see the true mind -- which is no mind. The old man will die and the new man will discover to his inexpressible joy that he has never existed! Sarah asks if exploring the subconscious is dangerous, if it can turn up nasty thing. Cho-Je explains that their way uses the power to help. But he must end the interview to meditate.

Mike then asks if the powers they are developing could be used for evil. Cho-Je reassures him that could never happen in his monastery.

Clegg is still upset by his visions. The Doctor asks abound bending forks but Benton arrives, see the IRIS machine and, not realizing the Brigadier is there, asks the Doctor if he is taking up hair-dressing. The Brigadier chides him and an abashed Benton explains that a package has arrived addressed to the Doctor, the Brigadier, Captain Yates or Sergeant Benton. When he explains that the package is from South America, the Doctor realizes it's from Jo Grant.

The Doctor eagerly grabs it, but then hands it to Clegg. The Professor sees that it has come a long way -- not just from South America but from the star. It's not a meteorite, but something beautiful, a crystal.

The Doctor and the Brigadier realize it is the blue crystal from Metabilis 3. He opens it up and holds up the sparkling blue gem.

Sarah and Mike overhear some chanting in the monastery. They quietly peer in to see a group of men meditating to a tape of monastic chants. Sarah asks what they are meditating about and Mike explains they are not meditating "about" anything. They're supposed to be watching their tummies as they breath. Sarah jokes they are contemplating their belly buttons.

They get ready to leave but are approached by Lupton and Barnes. Mike introduces them. Sarah is about to explain about the accident on the road, but Mike deflects her. When Lupton asks is they want to have some tea, Mike suddenly says Sarah Jane has to leave right away and drags the protesting girl off. Lupton delightedly watches as Mike guides Sarah to his car and drives away.

Mike explains to Sarah who Lupton was. He speculates the Lupton created the hallucination of the tractor. Sarah asks why they are running away but Mike explains they will return later in secret.

The Doctor reads a letter from Jo. She explains that they haven't found the mushroom Cliff is seeking. But they are having problems because the Indians don't like the crystal. So she's sent it back to whoever happens to be around.

Sarah and Mike sneak back into the monastery through a window but are caught by Tommy. He thinks they are playing a game and Sarah acts on this, saying it's a secret game and he shouldn't tell anyone about them. He spies her broach, comments on how pretty it is and she gives it to him. He wanders off, cooing over the pretty object. Mike taunts Sarah about her "shameless display of feminine wiles" which Sarah says is nonsense.

They sneak into the basement and hide as Lupton and his followers arrive, brushing against numerous spider webs. The men begin their chanting and cymbal-crashing once again.

The Doctor is still reading the letter when Clegg begins to sense something. Suddenly, the lab starts shaking as fire glows deep inside the crystal. Objects fly all over the lab as the Doctor struggles to get the crystal out of Clegg's hands. When he does, the Professor slumps in his chair, stone dead.

Sarah Jane and Mike Yates are investigating the mysterious events at monastery in rural England. They watch as a group of men, led by the enigmatic Lupton, chant around a Mandela. And amidst a bright blue glow, a giant spider materializes.

One of the men tries to run but the spider blasts him down with a flash of blue lightning. Lupton tries to banish it but it speaks to him! It promises to give him the power he seeks. It instructs him to turn around and then, to everyone's horror, leaps on his back. It disappears and Lupton turns around with a strange smile on his face.

The police have removed Clegg's body from the lab. The Brigadier asks what Clegg died from -- was it the crystal? The Doc realizes that Clegg was connected to the IRIS machine when he died. Perhaps it recorded his thoughts. He switches it on and watches as spiders appear on the screen.

Lupton's unconscious colleague is carried away. They ask him where the spider has gone but he doesn't answer, telling them to go back to their rooms and not talk to anyone. Barnes asks if he's all right and Lupton replies that he's never felt better.

The Doctor switches off the IRIS and decides to look into the crystal for himself. The Brigadier worries about the danger and Benton suggests he try first, since he's expendable. But the Doctor doesn't want to risk the Sergeant's life now that Clegg has been killed.

Mike helps Sarah out a window and urges her to tell UNIT what's going on. She realizes she doesn't really know what's going on, but Mike tells her to just tell them what she saw. He will try to speak to the abbot.

But then he sees Barnes and Lupton in the hallway. Barnes asks if the spider is a demon and Lupton assures him it isn't. He explains that the spider is still there and that, if he concentrates, he can hear it speaking in his mind. The spider tells him that Barnes is stupid -- he should be sent away. Lupton tells Barnes the spider has said he looks tired and should get some sleep. Barnes worries that he won't be able to sleep after what he's seen.

Lupton is about to head to his room but the spider stops him. She can feel the crystal. She explains that she has come to get a crystal -- one that will give them immense power. She tells him to concentrate and he sees a man staring into the blue light of a crystal.

He is seeing the Doctor staring into the Metabilis crystal in a rapture. The Brigadier calls out to him, but the Doctor is unresponsive. Benton arrives with coffee as the Brigadier calls the Medical Officer (a certain Lt. Sullivan). But even as he calls the MO, the Doctor begins speaking, revived by the smell of Benton's coffee.

Before Benton can explain how he makes his coffee, the Brigadier asks about the spiders. The Doctor instead launches into a story about his youth. He tells them that when he was a young man, a hermit lived in a mountain behind his house. He spent some of the best hours of his life with the hermit. It was there he first learned to look into his own mind. And when he looked into the crystal, all he could see was the face of his old teacher.

Yates goes to talk to the abbot K'anpo, but is stopped by Tommy. He threatens to hit Mike if he bothers K'anpo. He notices a necklace Mike is wearing and Mike gives it to him. Tommy, delighted, goes away with one last order for Mike to got bed. Yates waits, then starts heading back up the stairs. But he is stopped by Lupton, who tells him to heed Tommy's advice. Mike retreats beneath Lupton's confident gaze.

The next morning, Sarah tells her story to the Doctor as he continues to examine the crystal. But the Time Lord is not really paying attention, concentrating on the crystal lattice, realizing that it reflects thought. But he suddenly realizes Sarah has gotten to the part of the story about the spiders. He eagerly asks her to repeat it.

Lupton arrives at UNIT and speaks to a soldier working on the Whomobile. He asks about the Doctor and is pointed in the right direction. But the UNIT man then asks for a pass. Lupton responds with a bolt of blue lightning that knocks him to the ground.

Sarah gazes at the crystal as the Doctor explains where he got it. He tells her that it has strange properties -- it can affect the mind, clearing and amplifying it. She wonders if the giant spiders want it back but the Doctor explains there weren't any spider on Metabilis 3.

Benton sees Lupton in the hall and tries to stop him. But Lupton knocks him out with another bolt of lightning.

The Doctor realizes that the spiders could be coming from a different time on Metabilis 3. As he speaks, Lupton peers in and sees the crystal. The spider tells him to concentrate.

As Sarah muses on how calmly they can discuss such outrageous things, the crystal vanishes. It appears in Lupton's hand, who knocks out the recovering Benton again and runs out of the building.

The Doctor and Sarah find Benton in the hall and he explains what happened. Lupton exits the building and sees the Brigadier. As the Brigadier opens fire, he races across the lot and finally jumps into the Doctor's car and races off. Benton starts up Bessie and they all jump in to give chase.

They drive the Doctor over to a tiny helicopter and then begin a long chase after the Whomobile. The Doctor directs the chase from the copter. They race past a policeman who roars after them.

They finally track down the Whomobile, only to find it empty. The constable tries to get an explanation while Lupton watches from hiding. The spider urges him to steal the helicopter. He doesn't know how to fly it, but she insists they can figure it out. He breaks cover, jumps into he helicopter and takes off. The Doctor and Sarah pile into the Whomobile, which launches into the air in pursuit.

The constable tries to report in, decides no one will believe him and instead reports in sick.

Sarah spots Lupton's helicopter and they pursue him until he runs out of fuel. The spider makes him land and he then steals a motorboat. The Doctor and Sarah reach the shore as he leaves and the Time Lord jumps into a hovercraft. He cuts across the land, racing over a vagrant and closes the gap.

The Doctor, after a long chase, has just managed to capture Lupton, who has stolen the blue crystal of Metabilis 3. But even as the Doctor jumps on Lupton's boat, Lupton vanishes into thin air.

Tommy is walking down a hallway in the monastery when he sees Lupton materialize out of thin air. He spies the blue crystal and is fascinated. Cho-Je passed Lupton in the hallway with a contended grin.

Exhausted but triumphant, Lupton stumbles into his room. The spider promises him the crystal will give him more power than he can imagine. But she cautions him to cloak his mind -- her sisters on Metabilis 3 will kill him if they know his thoughts.

A link forms between them and they can see the home of the spiders -- a council chamber filled with huge spiders sitting on blue benches. On a raised platform sits the biggest spider -- the queen. Lupton and his host report their success and they are told to hurry back. Lupton wants to know how he will be rewarded but the queen dismisses him as a "two leg". The queen says his reward will be to serve them in their conquest of the Earth -- the secret plan of "the Great One". At the sound of the name, all the spiders chant, "All Praise to the Great One". Shortly after, the power is exhausted and the link breaks.

Lupton is almost dead and opens the window for some fresh air. The spider advises him to rest and regain his strength and he collapses into bed. She then reappears on his back and scuttles off.

The Doctor and Sarah arrive at the monastery and, with Mike, confront Cho-Je about what happened. Cho-Je calmly explains that he saw Lupton in the corridor at the precise time they claim they were chasing him -- so he couldn't have stolen the crystal. As they talk, both Barnes and the spider listen in.

Barnes wakes up Lupton and explains the situation. He sees the crystal and realizes that the Doctor's story is true. He warns Lupton that they are in great danger, messing with things they don't understand. When Lupton tells him the spider has gone, Barnes pushes him to run away.

Lupton instead explains why he came to the monastery. He was a salesman but was fired after 25 years of service. As he talks Tommy peers in the open window and snatches the crystal.

Lupton continues, telling Barnes that he came to the monastery to get power -- power to take over his old firm, the country, even the world. He'll make everyone else grovel. Barnes is appalled -- he just wanted to find peace of mine.

Tommy goes into a small cupboard under the stairs. He opens a chest and takes out a box filled with pretty trinkets. He happily puts the crystal in.

Lupton explains to Barnes that once he controls the crystal, he won't need the spiders anymore. But as he speaks, the spider returns and tells him Cho-Je is coming for him. Barnes can't hear the spider and she tells Lupton to send "this fool" away. Lupton gets him to leave.

The spider wants him to meet with the Doctor but Lupton refuses. She then twists his mind, creating tremendous pain. She mocks him for claiming he won't need the spiders anymore as he begs her to stop. She relents. But then he figures out what she did and turns it back on her. The spider writhes in agony as Lupton makes her grovel. Finally, he lets up and she admits he is much smarter than the two-legs on Metabilis 3. He boasts that he's smarter than most of them on Earth, too.

She agrees to avoid the Doctor and return to Metabilis. He's not sure he wants to go back and be a slave. She agrees that the queen is arrogant and confesses that she doesn't like the queen any more than Lupton Perhaps they can help each other when they return.

She then jumps on his back and returns to his mind. Lupton reaches for the crystal and realizes it has disappeared.

The Doctor pushes Cho-Je to let him see Lupton soon, but the monk delays, espousing a more philosophical outlook. Tommy looks in and beckons Sarah over. He wants to give her a present and she agrees to go with him. Cho-Je finally asks Mr. Moss to bring Lupton to them.

Lupton and Barnes can not figure out what has happened to the crystal. The spider then warns that the power is building and they will soon have to return to Metabilis 3. If the queen finds out they don't have the crystal, she will kill them. He decides they have no choice but to bluff.

Tommy takes Sarah to his cupboard. While he's inside, she spots Lupton talking to Barnes and Moss. Lupton instructs Moss to tell the Doctor he can't find him and goes to the basement. Sarah is eager to follow. Even as Tommy emerges with the crystal, she tells him to find Mike Yates and explain she's gone into the cellar. She is in such a hurry she doesn't see Tommy holding out the crystal to her.

Sarah sneaks down into the basement and watches as Lupton spreads out the Mandela and begins to chant.

The Doctor is pacing Cho-Je's room when Tommy arrives and tries to tell them where Sarah has gone. They don't pay attention until Moss returns, telling them Lupton can't be found. Tommy finally gets them to understand and they hurry off to the basement.

Lupton's chanting grows. A blue light envelopes him and he vanishes. Sarah, astonished, steps forward onto the Mandela as Mike and the Doctor arrive. They push past Barnes at the cellar door but can only watch in astonishment as Sarah vanishes.

Sarah finds herself in a barren wasteland. She looks around and see Lupton walking toward the cliff. But she is grabbed from behind before she can follow.

When Mike and the Doctor emerge from the cellar, Barnes is gone. The Doctor decides to follow Sarah to Metabilis 3 in the TARDIS. Mike is skeptical that he can make it but the Doctor tells him he fixed the coordinates on his last visit. Mike then asks how he will know where on the planet to find Sarah and the Doctor can only reply that he trusts the TARDIS to find her. Mike laughs that the Doctor talks about the TARDIS as though it were alive. "Yes, I do, don't I?" answers the Time Lord cryptically.

Sarah is brought into a village. Her captor - Tuar -- thinks she is a spy but an old man named Sabor persuades them to let her go. Sarah explains to a woman named Rega that she's not a spy. Who would she be spying for -- the spiders?

The word "spiders" frightens the villagers, who refer to the spiders as "eight-legs". Now convinced that she is a spy, they push her toward a cliff, but Tuar's brother Arak stops them. He points out that she's wearing strange clothes. Sarah then explains that she's from Earth and they ask if she came in a spaceship like their ancestors.

Just then, a trumpet rings out. The villagers realize an eight-leg is coming and they hide Sarah.

A group of human guards march in, carrying a pallet with the queen spider on it. They call out for Arak, for having attacked a guard. If he does not surrender, they will kill one man in each family. Before Arak can surrender, however, Sabor, who is his father, steps out. He first pleads that the guard was a cruel to the villagers, but the queen is unsympathetic. He then tells her he helped Arak flee and she decides he will go in Arak's place -- which Arak explains to Sarah means he will be eaten by the spiders. Rega runs out to him but the guards stun her with a staff fixed with a blue crystal.

But in the confusion, the queen spots Sarah leaning out of the door. The guards rush to arrest her and she steps out to keep them from catching Arak.

The Doctor has arrived on Metabilis 3 to find the spiders in the process of capturing Sarah. He fights with the guards only to be struck down by a lightning bolt from their staff.

As the guards struggle with the villagers, one suggests that the queen leave. He's never seen them so rebellious before. They notice that Sarah is gone, but decide the villagers are too restless to stay. They withdraw, taking Sabor with them.

Back on earth, Mike watches as Lupton's friends go into his room.

The villagers return to their houses while Sarah kneels over the Doctor. The villagers are sure he is dead and want her to get in before curfew. But even as they try to drag her inside, she see the Doctor move. He is indeed alive and starts groaning.

Mike listens at the door to Lupton's friends. They are scared, wondering what's happened. The doorknobs starts turning and they fling it open to reveal not Mike, but Tommy. He's come to clean the room but couldn't read the "Do Not Disturb" sign on the door. They shove him out and Tommy tries to read the sign, then muses that he should do some reading. After he leaves, Mike emerges from hiding and returns his attention to the door.

The Doctor has been taken into Arak's house. He is fading fast. Sarah holds his hand, keeping up hope.

The queen is brought into the council chamber and finds Lupton casually sitting in her place. She is outraged at his insolence but Lupton's spider challenges her right to rule. The queen wants them both killed but Lupton points out that they still need the crystal. The queen reminds them that it is the Great One who wants the crystal, but Lupton says she will have to wait until he's been rewarded. This blasphemy bothers the spiders but Lupton's spider stands by him.

The queen tries another tack, telling them they were followed. The male is dead, but the female lives and is a danger to them. She suggests that until Sarah is captured, they should delay any discussion.

Tommy takes the blue crystal out of his box. He then picks up a children's book and tries to read it. But he struggles badly. But then he looks up and see the crystal glowing. It mesmerizes him and he slowly reaches out to them gem. When he touches it, he falls unconscious to the ground.

Even as Sarah continues to stand vigil over the Doctor, Tommy wakes up and begins reading the book again. Suddenly, it is easy. With increasing alarm, he rapidly reads through page after page.

Arak is raging against the spider tyrants and wondering if they should try a rescue. Tuar suggests they attack the spiders directly but Arak says it would be no use. Sarah explains that the Doctor could help them if he were healthy. The Doctor speaks and manages to ask her to get a machine out of the TARDIS. Sarah takes his key, determined to get it despite Arak's warnings.

She goes into the square, evades the guards and enters the TARDIS. After a moment, she steps out with a leather satchel. But she is caught by Lupton, who taunts her that this is one story that will never be published.

Arak wants to rescue her but his brother stops him, warning that the village might be wiped out if he's caught. He is frustrated that he can't act against the spiders. But then he spots Sarah's dropped bag. He quickly slips out and grabs it.

They take out a strange device and give it to the Doctor. He flips a lever which starts a very loud noise and ends with a massive electric discharge. The Doctor, obviously much better, thanks them and falls into a natural healing sleep.

Tommy finds the library in the monastery. He pulls down a book and beings reading Blake's Tyger of Wrath. He calls it pretty -- then corrects himself to beautiful. He starts pulling down more books.

Sarah is thrust into the spider larder. She sees Sabor trussed up in a web. She tries to run but the guards knock her out.

Barnes and his friends are again deciding what to do. Mike knocks on the door and Barnes makes the others hide before admitting him. Mike explains that he wants to talk but a panicked Moss knocks him out.

Dawn breaks on Metabilis 3 with the ringing of bells. The Doctor sits up, bright and awake.

Sarah also wakes and finds herself wrapped in web. Sabor explains that it is no good struggling -- she'll be eaten soon enough.

The Doctor has breakfast in the village. Slowly, the villagers tell the Doctor their situation at the same time as Sabor tells Sarah.

It turns out that 433 years ago, an Earth colony ship crash-landed on Metabilis 3. The spiders were blown from the crash into a mountain with blue crystals. The crystals made the spiders larger and smarter. But the time they found out about the spiders, it was too late. They were subjugated by both the spider's fearsome mental powers and just plain fear. The spiders maintain a reign of terror -- having recently wiped out a village of 216 people because they were hoarding food.

The Doctor asks the villagers to gather stones. He has a theory he wants to try out.

Mike wakes up on Earth, but finds he's been tied up.

The Doctor begins to test stones with his machine. He explains that there may be a stone that will block the spider attacks. Finally, when he tests one gray stone, the machine rings out with a loud tone.

Shortly after, he set off for the spider lair, the machine and a gray stone with him. As he ascends the mountain, Sarah tries to get out of her cocoon. Sabor is no help, telling her to give up -- they have no hope of any rescue.

The Doctor enters the spider lair and a guard tries to shoot him with a staff. But he uses the machine to absorb the blast. The guards jumps on him, knocking the machine free. Before the Doctor can get it back, Lupton appears and orders the guards to kill the Doctor. But the chief guard stops them -- he has orders from the queen to arrest Lupton. They drag him off to the council. The Doctor casually tries to walk away but is stopped.

At the council, Lupton's spider tells him that the others know they don't have the crystal. They have traced its vibrations back to Earth. But Lupton is unflappable, telling them he never claimed it was on Metabilis 3 -- it's still hidden. And they still need his help if they want to invade Earth.

His spider points out that the queen has once again endangered the Great One's plan with her mistakes. She wonders if the queen is too old and perhaps another coronation is needed.

But the queen plays for time again -- telling them she will talk to the Great One and get her advice.

The bound Doctor is fascinated with the experience -- thinking this must be what it's like to be a fly. He keeps up good spirits, joking about their situation. Sarah wonders why the spiders didn't take the crystal in the first place, but the Doctor reminds her that he visited long before the spiders arrived.

The Doctor then reveals that Arak is planning to attack. Sabor is appalled at this. But before the Doctor can explain about the stones, the guards return. They pull a knife on Sarah, but then just cut her free. As they drag her away, the Doctor calls out for her to stall the spiders.

Arak is preparing his attack. His mother tries to stop him but they are insistent. They put on head bands with the gray stones and call out "Death to the Eight-Legs!" which slowly turns into "Death to the Spiders!"

The Doctor, ignoring Sabor's negativism, starts to wriggle free, using a trick he learned from Harry Houdini (although it takes a long time for him to remember the name). He rushes after Sarah, promising to come back and rescue Sabor.

Sarah is brought before the queen, who sends the guard out and reassures the girl. She explains that she doesn't agree with the council's plans -- she thinks the invasion of Earth would be a mistake. She wants peace. She will help Sarah get back to Earth to get the crystal. Sarah asks about the villagers and the queen promises to let Sabor go and listen to the villagers' grievances. Sarah asks what she needs to do.

Barnes releases Yates and asks him what they should do. Mike suggests they try to re-establish the link so Lupton can return. Barnes wonders why he wants to help and he points out that Sarah is gone as well. Barnes agrees to work with him.

Lupton and his spider whisper in the council chamber. He wants to go to Earth and get the crystal to open the path for invasion. But the other spiders want to hear the queen's plan first. They don't trust Lupton's spider -- especially now that she's allied with a two-leg. Lupton's spider then turns on him, telling him she is loyal to her sisters. When he tries to assert himself, the spiders blast him with pain. His head fills with their voices telling him "You will obey!" He finally agrees. Her loyalty to the council now established, Lupton's spider decides they will go ahead with their plans for invasion.

The Doctor is wandering through the lair when he hears Sarah's voice. He hurries toward the sound.

Tommy is now reading some quite complex books on the nature of intelligence. He doesn't understand what has happened to him. He then decides to ask Yates about it.

He opens the door and see Barnes and Yates agreeing to meet in the cellar. He retreats into the cupboard and thinks about all he's heard and seen -- Lupton's materialization in the hall, Sarah's disappearance. He finally decides to talk to Cho-Je. He hides the crystal and goes to see the monk.

The Doctor hurries through the blue tunnels, following Sarah's voice. But then a spider voice rings out and tells him to stop before he gets killed. He asks about Sarah and the voice cackles, then calls out to him with Sarah's voice again, singing "Pop Goes the Weasel" with the final line in his voice. He asks who it is and identifies herself as the Great One. She tells him that he will see her in good time -- but only when he brings back the crystal. She explains that it is the last perfect crystal of power. She has searched all time and space and must have it.

He refuses but she laughs at his pride. The Doctor winces in pain and starts marching around in circles as she cackles with insane glee. "Is that fear I feel in your mind? You're not accustomed to being frightened, are you Doctor? You are very wise to be afraid of me!" The insane spider then demands that he go and get the crystal, shrieking angrily at him that she must have it.

In the monastery the men chant over the Mandela. The spiders are also chanting, establishing contact. Their scouts are now ready. Lupton warns them to be careful and they agree to use secrecy. A spider goes to the center of the room and vanishes.

Barnes thinks it isn't working but Mike insists they keep trying. As they continue, a spider appears in a dark corner. More spiders vanish in the council chamber and appear in the corners of the cellar, surrounding the men.

Tommy explains events to Cho-Je. He says they should tell the abbot -- but only when they know what to tell him. He tells Tommy to get the crystal while he finds out "what these naughty chaps are about."

Tommy then asks Cho-Je why he's not surprised in his own change. Cho-Je simply replies that when everything is new, can anything be a surprise?

The Doctor finds his way through the blue caves, eager to find Sarah and escape.

Cho-Je bursts in on the men and tells them to stop. He warned them about this. But a spider scuttles out and strikes him down with a lightning bolt. They men try to run and Mike is struck down. Tommy appears and watches in horror as the spiders close in. He decides to go to K'anpo.

The Doctor finds Sarah. She takes his hands as they hear Arak and his men attacking. They vanish as Arak arrives and cuts Sabor free.

They appear in the village. The Doctor asks Sarah how she learned to do that and she explains that the queen taught her. Nesta comes out and Sarah explains that Arak's attack is succeeding. She then drags the Doctor into the TARDIS and they take off.

Lupton's friends are being taken over by spiders when the TARDIS materializes in the cellar. The Doctor and Sarah check the bodies of Cho-Je and Yates. Barnes tells them they are only alive from oversight. The men start firing blue bolts at the Doctor but he absorbs them with a dark crystal. Tommy then appears and tells them to run, taking the lightning bolts attack with little effect.

They lock the door as the men pound on it from the other side. Sarah comments that Tommy is just like everyone else, to which he answers, "I sincerely hope not." Tommy then leads then to the abbot.

They are brought to an ancient Tibetan man. Sarah asks the Doctor about the crystal but he doesn't answer. He greets the abbot in Tibetan, apologizing for not bringing him a scarf. K'anpo cryptically replies that no such symbol is needed between them. Tommy then goes out to guard the door.

K'anpo asks the Doctor for his story. The Doctor begins but not before asking the abbot if they've met before.

In the cellar, Moss tries to run away but the spiders make him stay to get the crystal. They can feel the vibrations. (Note, this scene was added to the reprise in Part Six).

The Doctor has finished explaining the situation to K'anpo. The abbot wonders if the spiders should just be allowed to have the crystal. The Doctor replies that nothing would stop them from taking over the world -- or even the Universe itself, Sarah adds. The Doctor wonders where the crystal is and the Abbot reveals it, explaining that Tommy gave it to him.

Sarah suddenly demands the crystal in the queen's voice. She hits the Doctor with a blue bolt. But K'anpo is calm. He tells her to concentrate. The massive queen appears on Sarah's back as she begins to fight the spider.

Sarah and the Doctor have returned to Earth and met K'anpo. But they have been followed. As the queen-possessed Sarah demands the crystal, spider-possessed men attack Tommy, trying to break down the door.

The Doctor and K'anpo work to break the queen's hold on Sarah. The Doctor tells her to look into the crystal. The queen tries to stop her but the blue glow captivates the young woman. Sarah's own voice finally begins to sound from her lips. She struggles against the queen and finally breaks free. The spider dies, falls from Sarah's back and vanishes.

Tommy endures the ongoing assault of lightning bolts, hurt but not beaten. Barnes realizes they need to try a different approach. They quickly form a circle and begin chanting to concentrate their power.

Sarah apologizes to the Doctor for her actions but he assures her she did fine. K'anpo points out that everyone is apt to surrender to domination -- even the most strong-willed. Looking at the Doctor, he comments that "not all spiders sit on the back." The Doctor explains to Sarah that K'anpo means the Doctor's own greed for knowledge that made him take the crystal in the first place.

Suddenly, the Doctor realizes something. He turns to K'anpo and tells him he knows who he is. They shake hands and the Doctor explains the K'anpo was his teacher -- his guru as a young Time Lord. Sarah realizes this means K'anpo is a Time Lord. The abbot explains that the discipline of their people wasn't for him -- although the wasn't quite as naughty as to steal a TARDIS. He just regenerated and fled to Tibet.

Sarah asks if Cho-Je is a Time Lord. K'anpo laughs that Cho-Je is a Time Lord in one sense -- and in another sense he doesn't exist. He is a projection of K'anpo.

Cho-Je wakes up Mike Yates and says they must hurry. They stumble out of the cellar toward the abbot's residence.

Barnes and his men continue to focus their power. The spiders are also meditating back on Metabilis. They explain to Lupton that they are sending power back to Earth.

K'anpo says that the moment of truth is coming for both of them. He asks the Doctor if he knows what to do. He must face his fear. The Doctor recalls how the Great One taunted him for being afraid. K'anpo insists that there is no other way out of this. He hands the crystal over and the Doctor tells Sarah he will give it back to the Great One. Sarah is alarmed -- the radiation in the cave will kill him. But he is determined. He must go and face his fear.

The men outside break their circle and raise their hands. They fire off a ferocious blast of mental energy at Tommy. Even as they fire, the Doctor takes K'anpo's hands in his, taking part in his mental powers.

Mike steps in front of Tommy and is struck down. Tommy is devastated and bends over Mike, letting the men rush the room. But even as they come in and blast down K'anpo, the Doctor vanishes into thin air. They realizes that he has gone to the cellar and run out, leaving Sarah to look over the mortally wounded abbot.

The Doctor reappears in the cellar and takes off in the TARDIS just ahead of Barnes' men. He appears on Metabilis 3 where he is greeted by a victorious Arak. The Doctor tells them he needs to go to the crystal cave and they agree to lead him there.

Tommy bends over Mike, worried that he might be dying. Cho-Je tells him to take him into the abbot's room.

Arak brings the Doctor to the spider council chamber. The Time Lord realizes that they didn't win the battle after all. The spiders taunt him, asking if he really thought the two-legs could beat the eight-legs. They asks him why he has returned and he shows them the crystal. They demand it but he tells them he will only return it to the Great One herself. He asks if any of them would dare oppose him. Lupton tries but is stopped by the spiders. They explain that the Great One is all-seeing, all-knowing, all-powerful. They must obey her. They acknowledge that the Doctor has beaten them but are grateful that he will die anyway. Arak and Tuar reluctantly let him leave.

Lupton then loses it. He yells at the spiders that they've cost him his chance at power. They are infuriated by the use of the word "spiders". He finally moves to hit the new queen but she strikes him down.

K'anpo lays his hand on Mike's head. He explains that Mike' compassion protected him from being killed -- just as Tommy's innocence protected him. To the delight of Sarah, Mike stirs and wakes. But K'anpo slumps back into his chair, dead.

Cho-Je reassures them but then vanishes. K'anpo's features blur and change before reappearing as Cho-Je, who finishes his sentence, telling them not concern themselves. He is only regenerating. Tommy calls him Cho-Je, but he replies that it is really K'anpo. K'anpo laughs and asks Sarah if she will put this in her magazine.

The Doctor returns to the cave of crystal. The Great One lets him in once he confirms he brought back the blue crystal. He enters and see a truly monstrous spider dominating the huge cave. He asks her to take the crystal and leave the humans alone. But she doesn't care about one planet amongst millions.

The Doctor asks why she wants the crystal. She indicates a crystal web above her head and explains that it amplifies her mind. One perfect crystal is all that is need to finish it. Then her every though well resonate in the web and grow in power. The Doctor tries to reason with her, pointing out that she has built a positive feedback circuit that will increase her mental power to infinity. She cackles that it will make her the ruler of the Universe.

The Doctor is fading from the radiation. He tries once again to explain that she will only destroy herself if she tries this. She mocks the way the radiation is destroying his body. She will grant him one last favor -- he can watch her triumph. The crystal leaves his hand and moves up into the web.

The Great One cries out in triumph. The Doctor watches in growing illness as she calls out for all to praise her. She tells the planets, the stars and the galaxies to bow to her. But after a moment, a bright glow envelopes her bloated body and she screams in terror and agony. Her mind is on fire from the influx of energy. The Doctor races out as the cave collapses around the thrashing spider.

In the council chamber, the spiders are dying, curling up as the Great One's death throes kill them. Arak and his men are suddenly free and they run for their lives.

Back on Earth, Barnes and his men stop meditating. Dead spiders appear on their backs and drop to the ground.

The Doctor finds the TARDIS and takes off as the mountain explodes.

Three weeks later, Sarah is sadly tidying up the Doctor's office. The Brigadier arrives and she explains that she came back to see if the Doctor had returned. The Brigadier tells her that once the Doctor disappeared for months -- and when he returned, he had a new face. Sarah laments that the Doctor knew he was going to die but went back anyway.

Suddenly, the TARDIS materializes in the corner. The door opens and the Doctor stumbles out. He mumbles that he got lost in the time vortex but the TARDIS brought him back. Then he collapses onto the floor.

The Brigadier grabs a blanket and puts it under the Doctor's head. Sarah asks him why he went back and the Doctor again tells her he had to face his fear. It wasn't worth living if he didn't. "Tears, Sarah Jane?" he says, "Don't cry. While there's life, there's . . ."

But he doesn't finish the sentence. He stops breathing, his eyes fixed. Sarah tearfully closes them and looks up at the Brigadier in despair.

But with a whirring sound, the young K'anpo appears, floating in mid-air. He explains that the Doctor is not dead. Sarah introduces him to the Brigadier, trying not to break down.

K'anpo tells them that the Doctor's cells have been destroyed. But he is a Time Lord. K'anpo will give him a little push and his cells will regenerate. "Not again!" laments the Brigadier. K'anpo goes on to say that the Doctor's brains cells will be shaken up and he be erratic for a while. Then he vanished like a Cheshire cat.