On a dark planet, a Mutt creature crawls from a wrecked spaceship and picks up a bag but tosses it. Condo, a large man with a hook for a left hand, takes out a knife and cuts the thing's head off. He brings it to Dr. Solon in a castle. Solon is not pleased with the head of the insect creature. He wants a humanoid species, warm blooded with a central nervous system.

The TARDIS appear and the Doctor rushes out to the mist shrouded planet as a lightning storm approaches. He yells to the sky about someone dragging them a thousands parsecs off course. Sarah comes out and he tells her the Time Lords have interfered with the TARDIS. There is something going on that the Time Lords will not dirty their hands with. The Doctor sits on a rock much to Sarah's chiding. Sarah goes to see something as the Doctor plays with his yo-yo. She sees a space parachute -- a projection bubble. Sarah goes up a rock and looks into a valley. There a many crashed spaceships like a Sargasso Sea of space. Sarah goes to investigate as the Doctor practices his double loops. He wipes the TARDIS doors off where there is the message but he runs as Sarah gasps. He finds her backed away from the headless body of the insect. The Doctor tells her it was after the crash that the thing was killed. It was a mutant insect species widely established in the Nebula of Cyclops. The Doctor thinks he recognizes the stars -- he was born in these parts within a couple of billion miles. He doesn't answer Sarah directly when she asks if he's been to this planet before. Sarah spots the castle and as the rain picks up the pair head to the large object, watched by a strange witch like girl -- Ohica, one of the Sisterhood.

Solon has the head of the Mutt hooked up for tests on the motor reflexes. His lights go out and he has to set up a candle. He calls for Condo to fetch some lamps. He goes out of the lab to look for Condo, leaving something twitching behind a curtain.

Ohica reports the male and female in the valley below. She tells Maren the leader, who tells her they sense beyond the five planets. They even feel the silent gas dirigibles of the Hoothi in their bones. Maren, for months, has had a dream that the elixir of life will be taken from them. Ohica is the oldest, next to Maren. Maren shows her the door, unlocking it and opening it to reveal the flame behind, set in the wall. The Flame of Life which is low. Maren has deceived the others by flickering the flame with RhineWeed before each ceremony. They are only servants of the flame. The others should not know until the end is certain. The secret is known only to the Sisterhood and the High Council of the Time Lords. They always shared it with the Time Lords. The few vials left are for the Sisterhood. They think the two that have arrived may have been sent to steal the elixir. She tells Ohica to summon the sisters and they will form a circle.

Condo returns to Solon, who berates him for looking for his cut off arm again. Condo lies that he was looking for food. Sarah and the Doctor ring the bell; Solon sends him to open it. The Doctor has an umbrella in the rain. "Can you spare a glass of water?" Solon is overjoyed that after so long, humans are here. He acts very friendly to them and takes the Doctor's hat. "What a magnificent head. A superb head."

The Doctor laughs this off, "I have had several. I used to have an old grey model before this. Some people liked it."

Sarah: "I did."

The Doctor prefers this model. Sarah feels for the fire as they sit and she joins them. The Doctor thinks the accommodations are interesting. The planet is called Karn. The Doctor sees the bust of a head, "You seem very keen on heads..." Solon tells him his full name: Mehendri Solon. Solon covers the bust with a sheet as the Doctor thinks he recognized the face. The pair explain to Solon about a headless body they found. There were 15 ships wrecked in this one area. Solon thinks it is the belt of magnetic radiation that caused this. Condo brings wine. Solon berates Condo for not opening the wine, allowing it to breath. The Doctor tells him not to bother. Solon explains about Condo's arm. Condo was dragged from the wreck of a Dravidian spaceship and the only way to save him was to amputate the arm. Solon starts to give them meat.

The Sisterhood chants in a circle, "Sacred Fire, Sacred Flame." This allows Maren to see the TARDIS on her ring. She tells them to concentrate and they do. This brings the machine of their enemies here: the TARDIS appears in a vague mist and then fully forms in the Sisterhood cave-citadel. They feel the TARDIS without touching it. They deduce the Time Lord is the man that Ohica saw and that he is here to steal the Flame. Being their equals in mind power, the Time Lords can resist their power. Other beings they can destroy from within, send them mad with false visions. But Time Lords can close their minds to the Sisterhood. They reform a circle and begin to chant again.

Solon tells his guests that he doesn't usually feel a longing for his planet of origin. He sometimes looks up at the stars at night and wonders if he will ever see Earth again. Sarah says, eating, "I know the feeling." The Doctor knows Solon is a Terran neurosurgeon who specializes in microsurgical techniques in tissue transplantation. This castle is a former hydrogen plant built on typical Scott Bailey principals and Solon wrote a book about the techniques. Solon's time is considerably after Sarah's time. The Doctor comments that it was said by some that Solon joined the cult of Morbius. Condo is ready to use his knife to kill. Solon tells the Doctor that was just academic jealousy -- he just had to get away. Maren's ring shows her the Doctor drinking with Solon. They cause the doors to open and the chandelier to fall just after Sarah pours her drink into her bowl when Solon isn't looking. She hasn't had a drop but the Doctor has. In the blast, the fire goes out and the sheet falls off the bust of the head that Solon made. The Doctor avoids Solon's excuses and knows that it was a telepathic visitation. When Solon asks about what the Doctor knows about the Sisterhood, the Doctor touches his nose but seems a bit drugged...which he is. Before he passes out, the Doctor knows who the bust is of...Morbius, one of the most horrid minds that ever lived. When the Doctor passes out, Sarah fakes herself unconscious also. Solon holds the Doctor's head. Solon dreams of people admiring his handiwork a thousand years from now. Solon orders Condo to kill the girl but Condo hesitates. Solon is anxious for Condo to take the Doctor to the lab, nervous that Condo should mind his head. After they go, Sarah gets up and sneaks through the castle.

Solon examines the Doctor and finds a secondary cardio vascular system. This means the Doctor is a Time Lord and Solon now knows this. He thought as much anyway. The Time Lords are spineless parasites, they rejected Morbius's offer of power. They will be the first to pay for that. Sarah looks through the rooms. Solon tells Condo he needs proper lighting, thus the generators have to be repaired. The two leave the Doctor asleep on the slab in the lab. After they go, the Doctor, in a mist of skylike clouds, vanishes. Sarah hides in a hallway, against the wall, as Solon and Condo pass her by. Solon is talking about the Doctor's brain. After they pass, Sarah sneaks into a dark room... the lab.

Sarah turns away, thinking Solon is mad. She hides as Condo and Solon return to find the Doctor gone. Solon insults Condo and then realizes it is the harpies -- the Sisterhood and Maren's leadership in particular. Condo knows the Sisters see much -- they see with mind. They leave to get the Doctor back. Sarah leaves out of a door with flower images.

The Doctor awakens and is given a drink. He calls Maren matron. Ohica calls him Time Lord. "Please just Doctor, I hate all this bowing and scraping." Maren asks if he wishes to confess. "I have to confess that I really don't know." The TARDIS calibrators have been on the blink. The Doctor thinks their practice of teleportation is quaint. He mentions they should get a decent fork lift. He thinks he has lots of time to begin life -- life doesn't begin until 750, and he is only 749. The Sisters have spear heads with flame point designs on them. If he confesses his death will be made easy. The last thing he remembers was taking a glass of wine with Solon and Morbius. He wonders how he got that impression. A living mental contact. He felt the mind of Morbius. Morbius was executed for leading a rebellion and his body was placed in a dispersal chamber and atomised to the nine corners of the universe. Morbius's mind touched the Doctor...he felt his burning hatred. Morbius is alive. Maren was present at Morbius's execution. The Doctor will join him in death shortly, Maren promises.

Solon and Condo move toward the shrine. Condo asks if he should kill a sister who is getting wood for the fire. Solon tells him not to kill her -- Solon wants no trouble with the Sisterhood. Condo hears something -- Sarah in the rocks above hiding. She throws a small stone to distract him. More Sisters pass with wood. Wood for a fire that they plan to put the Doctor on via a stake. Maren has a powder that can spare him the anger of the flames. With his spoken confession, the Time Lords can never deny that they plotted against the Sisterhood. The Time Lords saved the Sisters. Maren tells him that was out of self interest. They depend on the elixir which no longer forms. The flame dies. It is the product of gases forcing up along a geological fault from deep in the molten core of the planet. Subterranean movement may cause it to lower. The Sisters tie the Doctor to the stake. The Doctor tells them they need scientific advice - this is why he might have been sent here. If the gases are sealed in the entire mountain could explode. The Doctor calls forth some previous type of explosive build ups: Pompeii, Kartapaxi, Mount Vesuvius, Poppa Kanta Pettle.

Solon hears the song of death sung by the Sisterhoods. He knows they are sacrificing the Doctor. Condo tries to stop him from going further but he plows on to the Sisterhood Shrine. Sarah sneaks after them. Solon interrupts the burning. He tries to apologize. Condo moves to protect Solon but Maren uses her ring to cause a power build up to divert Condo. The Doctor is delighted to see Solon, "That music was terrible." Solon wants a favour -- he never asked anything of the Sisterhood. He treated many of them. He asks for the Doctor's life to be spared. The Time Lords and the Sisterhood alliance no longer exists. Solon offers Condo to be sacrificed. Solon asks that the Sisters not burn his head and spinal cord. Maren tells him the Sisters know of his unnatural experiments. While the two verbally spar, Sarah, with an orange coloured shawl over her head, sneaks up behind the Doctor, takes a pair of cutters from his pocket, and cuts him loose. Solon apologizes and backs out with Condo following. The Sacred Flame, Sacred Fire song starts to be sung again. Maren goes into her speech as the offering is made and the fires are set at the Doctor's foot. Sarah is one of the dancers nearby but she doesn't light the fire. The Doctor waits until Maren's eyes are closed to back away. As the Doctor and Sarah run out, she opens her eyes and shoots her ring at Sarah. The Doctor gets Sarah out as Sarah seems hit by some blue power.

Condo is angered by Solon wanting the Sisters to kill him. Condo threatens to kill Solon, grabbing him with a hook and pulling a knife. Solon tells him it was a stupid joke. Solon gets free as Condo tries to cut his head off. Solon promises to put his arm back and take the hook off. Condo wants the arm back now. Solon sends him to the lab to get ready. He will fetch the arm.

Outside, it seems light again. The barbecue is off. But Sarah can't see, she's gone blind. The Doctor thinks the optic nerve was numbed and it will wear off. He tells her to come on and she says, "Not as the case may be."

"Oh Sarah," he says. If she wallows there in self pity, he'll bite her nose. She thought about selling flowers in Piccadilly when they get back. He yells at her to come on back to Solon's. She tries to tell him about his madness he has a headless body there. He takes her toward the castle.

Solon talks to a strange voice, a watery voice. A voice he calls Morbius. This plan was formed to fool the Time Lords. Solon has new techniques -- he can transplant limbs, organs, and create life. Morbius can see nothing, feel nothing; he'd rather die now. Solon desires to be the creator of Morbius, the voice says. Condo calls his Master from the secret alcove to greet the Doctor. The Doctor is sitting with his scarf on his legs. The Doctor was very touched by Solon's concern, he says sarcastically. Solon asks if they want some wine. The Doctor wants him to check Sarah's eyes. They have to go to the lab.

Ohica asks Maren what they shall do. Maren tells her that they have his TARDIS. Soon he will return for it. And then he will wish he had died in the flame.

As Solon checks Sarah's eyes, the Doctor sees the headless body. Solon shakes his head to the Doctor that there is no help but fakes that there is every recovery. Solon tells Condo to take Sarah back to the parlour. Whatever the truth is, the Doctor tells Sarah, she will hear it. After Condo and Sarah go, Condo being very caring for Sarah, Solon is forced by the Doctor to tell him there is some chance...the elixir of life. The Doctor will go back to get it. He leaves, Solon telling him, "Good luck." Solon calls Condo as he writes a letter. Condo leaves Sarah in the parlour. Sarah nearly trips over a chair. She hears a voice calling Sol--on. Following it slowly and nearly tripping over a step, Sarah moves toward it. Solon gives the note to Condo to give to the Sisters before the Doctor gets there. Solon smiles to himself.

Solon pulls Sarah out of the room but she lingers and overhears him talking to the brain which lights up. She hears him call it Morbius and "my lord." Morbius has a voice box attached to a stretched skin. She also hears that Solon sent the Doctor into a trap. Sarah locks Solon in. He threatens her life, telling her that when Condo gets back she will die. Sarah stumbles about to try to find and warn the Doctor.

Maren is giving the Sisters some of the potion from the sacred fire as the others chant. Only these five that she gives the elixir to will survive. She puts it back. Of these five Ohica is one of them. Ohica tells Maren that they both know what will happen. Ohica is brought the message that Condo brought. Maren wonders why the Doctor is coming, he is not a fool. Maren sends Ohica to warn the guards.

It is daylight again as Sarah feels her way through the rock patches. The Doctor enters the Shrine, "Ding Dong." A red-orange net falls over his head and the Sisters surround him. "We can't go on meeting like this."

Condo returns and hears Solon call him to free him.

The Doctor is told by Maren that the girl will recover. The effects of the ring are temporary. Solon knows this. Maren allows the net to be taken off the Doctor. A Time Lord could live on Karn without their knowledge. Morbius was a Time Lord. Maren saw Morbius vanish -- even the smallest atom. Solon was on Karn at that time. Many were here...they came from all across the galaxy to see Morbius's trial. Morbius betrayed the secret of the elixir to all. Morbius promised his followers the elixir and the scum of the cosmos came. The Doctor tells Maren she cannot continue dragging innocent space travellers to their death. He insists to stop the wrecking of spaceships if he is to help them.

Sarah falls and rolls down some rock steps. She feels her way around but moves right into Condo's legs, feeling them. He grabs her by the hair. Sarah tells him he is hurting her and begs him not to kill her. Condo thinks Sarah is pretty and finally lets her go but then grabs her arm. Condo thinks himself ugly. He tells her "Doctor dead," and picks her up in both his arms and carries her away.

Maren calls the Doctor's arrogance limitless. The Doctor talks Maren into letting him see the flame even though she insists nothing is to be done. She has served the flame for centuries. Ohica thinks the Doctor should see the flame. She tells Ohica to send the guards to the outer chamber -- no eyes outside the Sisterhood have ever seen the Flame of Life. The Doctor looks in--the heat from the flame causes oxidation of the chemicals in the rocks and then the chemical reaction of superheated gases into an elixir dripping from the rocks over. The Doctor tells them death is the price they pay for progress. The elixir is used by Time Lords only in rare cases, when there is some problem in regenerating. Otherwise, the Doctor claims, they would fall into the same trap the Sisters are in now: nothing here ever changes, no progress. He tells them to stand back and from his hair he takes a little demon and lights it and puts it in the flame. This makes the flame go out and the guards are sent to put him to the stake. He must now die. But the flame rises up higher than ever. "Soot, that's all," the Doctor gets off and warms his hands.

Sarah is tied to a slab. Condo asks Master not to hurt the girl. Solon mocks Condo, calling him a romantic. Sarah says to Solon, "And you think you're a bundle of laughs, aren't you?" Solon throws Condo out when he touches Sarah's head. Solon tells Sarah perhaps he will give Condo the hair off Sarah's head as a memento. Sarah calls Solon mad and insane. Solon rants and raves about others who called him that. And about his project. He recalls he needs the head and wonders why Maren hasn't sent the Doctor's head by now. Sarah is tied via hands and body.

Solon reports to Morbius and tells him that the Doctor is a Time Lord. "The crowning irony," Solon says.

"Fool," Morbius yelled.

"I'm sorry the pun was irresistible," Solon says. Morbius calls him a fool and lets him know the Time Lords must have found him and that the Doctor and Maren have plotted together against them. Solon thinks of all his work, all his lonely isolation. Morbius wants to flee, he has to get out of this time, and even suggests using Sarah's head. Condo listens to the two, secretly hidden. Morbius brings up the artificial brain case experiment Solon once talked of. He even made a brain case. There were problems with this: build up of static electricity in the cranial cavity, it would leak into the brain, upsetting the equilibrium, dislocating the neural centers once it did. He finds the case in a large canister and takes it out. Solon argues it should not be done, "There would be severe pain, there would be sear seizures!" Morbius tells Solon he will take the risks. There is no choice. Solon will do it. He lets the fluid out of the brain case.

The Doctor is out it seems. Ohica asks Maren if what they are doing is right. Sisters carry the Doctor toward Solon, who, with Condo is carrying the former brain housing jar to the lab from the hidden room. Solon sets Condo to a pump but it is near the mixed body he has made -- which includes Condo's arm! Condo gets angry and attacks Solon, who shoots him. They fight and knock the brain jar over and the brain falls over and onto the floor. Solon shoots Condo some more and picks the brain up with his hands as Sarah shouts for Solon to tell her what is happening. He releases Sarah to help him and grabs her to help him restore Morbius. He sets her on the pump. When she asks what if she makes a mistake, Solon tells her, if Morbius dies, she dies. Condo crawls into the hallway.

Many Sisters carry the Doctor horizontally through the lightning storm. One has a torch.

Morbius works. Sarah pumps every three seconds. He connects the case to a new harness. All that is left to do is disconnect the external power supply to the brain and test the neural feedback. Morbius's claw can move now. Solon asks if she has seen it. She can't see anything, she yells. The door ring sounds off. In a few minutes Morbius will live again. Solon yells for her to go and answer the door but realizes that Condo is probably dead. He leaves to answer the door, avoiding the Sister guards who leave the Doctor for him on the floor. Solon deduces that Morbius was wrong... the Sisters have given the Doctor to him.

Sarah's eyesight fully returns just in time for her to turn and dodge the menacing advances of Morbius, who overturns a gas tube and burns his claw. Sarah runs out to Solon and warns him. Before she runs out, she sees the Doctor on the floor as Solon runs out. "You thought I was I dead," the Doctor sits up and smiles to her relief, "You're always making that mistake." Sarah nods. She tells him he is too late.

Morbius sees himself in a full length mirror and smashes it. Solon arrives in the lab and calls himself his creator. The speech center isn't functioning properly. Morbius grabs Solon up and bear-hugs him down. Then it walks out.

Sarah is telling the Doctor about Morbius. The Doctor asks if she can read its thoughts through the glass tube. She doesn't think it funny. Morbius arrives and he tells her to keep calm but sees he is calm. The Doctor tells Morbius he remembers him and shakes his hand but is hit down. Morbius attacks Sarah again and she falls. She gets up and runs. Condo runs past the Doctor, seemingly kicking him in the head. Sarah rolls down a flight of steps. Condo comes to her rescue, saving her and knocking Morbius down. Condo takes out his knife to kill Morbius and they roll. In the end, Morbius gets on top and uses his claw to strangle Condo. Breathing heavily, Morbius stalks out. The Doctor recovers and goes out a door. Solon recovers also in his wrecked lab and takes out and fills a syringe. The Doctor carries a dazed Sarah to lay her down on a slab. The Doctor leaves her to rest and sleep. He finds Solon with a tranquillizer rifle. The Doctor hides behind the model head of Morbius. The Doctor is asked by Solon to help stop Morbius.

Morbius stalks the Sisters and finds one (named Kelia) among the wreckage of an old shrine and claws her to death, choking her at the neck. The Doctor checks the girl...she is dead. During a new storm they hunt the monster, which springs out at the Doctor. Solon watches coldly as it begins to strangle the Doctor but finally he shoots the stun gun at it. The Doctor calls this thing Solon made an unspeakable abomination. Solon calls it simple animal instinct. Morbius wouldn't want to aggravate the Sisterhood at this stage. The Doctor picks Morbius up over his shoulders, telling Solon the brain will be detached and returned to the Time Lords. The guard Sisters have found the dead Sister, Kelia. The Sister who found Kelia saw a creature and later found the Doctor and Solon hunting it.

The Doctor gives Solon five minutes and tells him either he disconnects it or he will do it his way...with pliers. The Doctor leaves and will be back to count the pieces. The Doctor wakes up Sarah and tells her he's done it. She recounts her dream: blinded, attacked by a monster made from butcher's leftovers, and knocked down a flight of stairs. She realizes it is real and asks where Mister Allsorts is. She also asks if Morbius was really that dangerous. There was a civilization on Karn once. Gone. And many other planets just like it, all destroyed by Morbius -- nothing but ashes. The Doctor finds the doors locked and laments that he should have stayed with Solon --Solon has locked the pair of them and the sonic screwdriver is in the TARDIS.

Solon is operating -- repairing Morbius.

Ohica asks Maren if it is right that they let the Doctor fight their battles for them. Maren claims there is no proof Morbius is alive. Solon himself is evil and the reviving of Morbius makes sense of Solon's evil work. Maren tells Ohica there is little they can do. Maren is too old and weak to leave the shrine. Ohica asks her to give her the order and she will lead the Sisters to Solon's.

Sarah tells the Doctor he has to do something -- Solon has to be stopped. The Doctor looks for HCN. Sarah jokes that they can drink themselves to death. The Doctor looks for something on the wall and tosses things out of the way...he finds a small vent that leads to Solon's lair. She asks if he wants her to crawl through that. He will use it to send a gas up to Solon. The Doctor mixes elements to make a gas that will stop Solon. If the two are still in the cell in a month, it hasn't worked. Solon finishes his experiment but coughs. He chokes and falls. Morbius gets up and drops Solon off his body. The Doctor has made cyanide. Morbius leaves.

The Sisters head for Solon's.

The Doctor tells Sarah how many seconds there are in a month. Morbius comes inside to tell them the plan did not work on him but on Solon. Morbius has the lungs of a birastropthe. Morbius wants his followers to rise up. The Doctor and Sarah tease Morbius to overheat his brain. The Doctor challenges Morbius to the mind bending contest with the necessary apparatus. The Doctor calls himself nothing, a mere nobody but he can still do Time Lord Wrestling -- it used to be a game but it can end in dead lock. They grab the apparatus and mind fight: in a small area of the apparatus between the two Time Lords, Morbius's face appears and goes back to his old face. The Doctor's face becomes his previous self...

Morbius's mind drives the Doctor back and Morbius asks, "How far Doctor, how long have you lived?" The face becomes the Second Doctor and then the First Doctor. Other faces appear as Morbius tells the Doctor he will go back to his beginning. Eight other faces appear -- either the Doctor or Morbius. The duel ends with the Doctor falling down and Morbius's brain case getting a power blast. Morbius whirls outside. Sarah tries to use smelling salts to revive the Doctor.

The Sisterhood uses flame to send Morbius away from them but they chase him. Ohica finds Sarah and the Doctor. Sarah tells her she thinks the Doctor is dying.

Morbius is chased by the Sisters up a high mountain. He is surrounded and he ends up falling over the chasm into a deep pit.