The next day Sarah, Luke and Clyde arrive at the home to visit the woman, Mrs Randall, a friend of Clyde’s grandmother. As she and Sarah discuss the nun, who has been seen by other residents in the past, Luke finds another woman outside, beckoning to him.

Back in Bannerman Road Maria’s mother has come to visit, hoping to make her new boyfriend jealous be temporarily leaving him. Although her ex husband is not impressed, Maria is far more jubilant at having her mother living with her again.

At the rest home Luke joins the woman, Mrs Nelson-Stanley outside, where he discovers she believes herself to be in Egypt waiting for her husband. However, she soon snaps out of her delusion, recognising Luke as the boy from the window, and after revealing she too has seen the nun, leads Luke away.

Inside Sarah talks with the owner of the home, Mrs Gribbins, who is far more sceptical of the story of the nun, thinking Sarah is chasing nothing but superstition in her search for a story.

In the grounds Luke is led to an ivy-covered plinth which the old woman, who reaches into the foliage and pulls out a battered tin box. Inside she reveals an ornate talisman, which she hands over to him to keep, with only one instruction: “You must not let her get it”. Luke takes the item; unaware Mrs Gribbins is watching them from the window.

In Maria’s room her mother enters, offering to take her daughter shopping. However, Maria has homework to do and the two are soon arguing, Maria distressed by her mother’s attitude to Sarah Jane and Luke, as well as her sudden appearance back into her and her father’s lives.

Clyde, Sarah and Luke leave Lavender Lawns, Clyde moaning about the elderly whilst Sarah explains to her young friends that everyone must get old. Clyde protests, claiming that when he is older the technology will be in place for his brain to be fused in a robotic body. They drive away, again under the watchful eye of Mrs Gribbins.

Maria’s dad consoles her over the previous argument, but she is still bitter about her mother’s negative attitude toward their neighbours. She then begins to turn on him, upset he seems to have moved on quicker than she has following his divorce, her life is changing and she isn’t prepared for it.

Meanwhile, at a nearby abbey, Mrs Gribbins arrives and knocks upon the door. When it is answered she asks to see Sister Helena.

In her attic, Sarah calls for Mr Smith and sure enough the giant computer appears from within one of the walls. Lavender. He begins to research the history of the Lavender Lawns Rest Home, but he finds nothing peculiar. He then detects the object Luke has been given and identifies it as alien. He is unsure if it is safe and as Sarah asks Luke where he acquired it, a moody Maria enters. Sarah decides she must talk with Mrs Nelson-Stanley, and she takes the young girl along with her leaving the boys in the house.

At Maria’s house, her mother is annoyed by her daughter’s row with her. She finds her ex-husband somewhat unsympathetic, he is disgruntled by the fact she seems not to notice how she affects her daughter by turning up only when it suits her.

At the Abbey Mrs Gribbins explains about the talisman and how it has been given to Luke. Sister Helena is annoyed that matters have now been complicated; the Abbess will want to see her. She is taken away to a room in which an elderly woman is seated in a chair. She raises her withered hands and removes her veil, causing Mrs Gribbins to scream.

At Lavender Lawns, Mrs Randall takes Sarah and Maria to Mrs Nelson-Stanley’s room, where they discover her husband was an archaeologist. He died some years ago and since then she’s gone apparently mad. Maria sees the talisman in a photo of the pair. Mrs Norman-Stanley soon arrives and Sarah asks where she got the talisman. She does not answer, and instead recalls her husband’s opinions of a race known as the Sontarans. Mr Randall explains the old woman talks at length about the Gorgon, a creature from old horror films.

Sister Helena arrives at Sarah’s house, looking for talisman. Luke reveals that he has it, but Clyde refuses to hand it over. Maria’s dad arrives and she lies to him about visiting for a donation to repair the Abbey roof, before leaving hastily. Clyde and Luke then explain Maria has gone with Sarah but will return soon. Clyde tries to explain to Luke about discretion before deciding they should return to the rest home to explain about the sister, unaware a hearse is following them.

Sarah and Maria realise Bea is not talking gibberish; Sarah has also encountered creatures known as the Sontarans. Mrs Nelson-Stanley digs out an old record whilst Sarah questions her about the talisman. She explains it was unearthed in Syria by her husband, and insists, “They mustn’t find it.” The sisters are looking for it, and they protect the Gorgon.

The two friends then return home, where Sarah unearths a book of Greek mythology. She explains that there were three Gorgons, one of whom was Medusa, a creature with serpents to hair who turned her enemies into stone with a single glance. She theorises that if Mrs Nelson-Stanley is right, then one of the Gorgons may still be alive.

Sister Helena pulls up in her hearse and meets Luke and Clyde at the roadside, promising not to harm them. She claims she wants to talk to them, and explains that the talisman is dangerous, “more than you can imagine”. She grabs Luke and puts him in the car with the intent of taking him to Abbey, leaving Clyde alone on the pavement.

Sarah explains to Maria that the Gorgon might be an alien, still alive since time of the Greeks. Clyde phones and explains what has happened to Luke. Soon he arrives back at the house and he, Sarah and Luke travel to St Agnes Abbey. Sarah bluffs her way inside with a fake identity, whilst Clyde and Maria sneak off around the back.

Sarah arrives in a library and is locked inside by one of the nuns. Meanwhile, Maria and Clyde sneak around the back of the Abbey and try to get inside, finding an open window through which to enter. They begin looking for Luke; worried they might find the Gorgon instead. They enter one of the rooms, where they find a statue of Mrs Gribbins. Suddenly the door opens and the nuns enter; they have been caught.

Luke is brought into the library, followed by Helena. As Sarah rejoices at having her son back, the Sister claims the kidnap was only to get her attention. Clyde and Maria are then brought in and they explain about Mrs Gribbins. Helena then explains that although the image of Medusa was a Greek embellishment, the creature was indeed one of the Gorgons, who now survives as the withered Abbess of the Abbey, whom generations of the Sisterhood have sworn to protect.

She tells them that of the three original Gorgons, only one remains. One was killed in the ancient days of Greece, when the key that helped the Gorgons come to Earth was stolen. Since then the Sisterhood have searched for it, only coming close some fifty years ago when Mrs Nelson-Stanley and her husband uncovered it. Sarah deduces that it was then that the second Gorgon died.

Helena then claims that the Gorgon just wants to go home to die, and Sarah reluctantly agrees to help her do so by handing over the talisman. She and Maria return home, whilst the nuns keep the boys at the abbey as insurance. The Gorgon is taken with them, accompanied by Helena and some of the other Sisters. Sarah returns to the attic and retrieves the talisman. She arms herself with her Sonic Lipstick then goes back downstairs.

Maria questions Helena about the Gorgon but she receives no reply. Sarah enters with key to the portal but threatens to destroy it unless the boys are let go. Helena warns that she has gone too far and the Gorgon is brought before her. She warns Maria not to look at its face and they turn away. The creature reveals itself to them, a withered humanoid figure with glowing eyes and a beam f light emitting from her mouth.

Having snatched the talisman the Sisters depart, leaving Maria left with her stone father. Sarah comforts her, claiming; “there is always a chance”. However, Maria is not convinced and instead blames Sarah for all that has happened, things would never have gone wrong had she not met her. Sarah hugs her, she understands.

Locked in the Abbey, Luke wonders why Mrs Nelson-Stanley would worry about sisters grabbing talisman if all it did was send Gorgon home. Whilst Clyde worries, Luke reads a book of the history of the building and discovers that there is a secret passage located in the room, activated by rotating a stone bust of Medusa placed on a plinth nearby. The passageway opens and the pair go inside.

In the attic Mr Smith explains Maria’s father has not simply been turned to stone; he has been subjected to a process similar to fossilisation, and the process is not yet complete; there may be a chance to save him. The process can be reversed but he doesn’t know how, all he can tell them is that they have 90 minutes before the process is irreversible. He explains that to help he will need more knowledge of the Gorgon, and Maria realises they must return to Lavender Lawns to talk to Bea Nelson-Stanley.

Luke and Clyde crawl through the tunnel and arrive in the garden of the Abbey, which is decorated with the fossilised remains of the Gorgon’s victims. Somewhat unnerved by this display of the creature’s power, they move to leave.

Maria and Sarah arrive at Lavender Lawns Rest Home but Sarah explains she must leave to return to the Abbey. Maria apologises for what she said back in the attic then departs to find Bea.

At the Abbey the Sisters arrive to open the portal, under the watchful eyes of Clyde and Luke, who remembers promising Bea he would not let them take the talisman, he has to stop them but he needs Clyde’s help. At the rest home Maria arrives in Bea’s room, but she fails to recognise her young visitor.

The Sisters arrive at the portal, a stone basin with an imprint for the talisman. They begin chanting; “Save the Gorgon”, and Sister Helena prepares to open the device, claiming the Gorgons have 100 million years to travel; the angle of ascension must be perfect, the portal will be open in one hour. She then begins to realise that the Abbess’ body is dying, they need a new carrier.

Back at the rest home Bea recalls again her husband Edgar and their time in Egypt. She remembers meeting the Sultan, who claimed he had seen the Yeti. Maria tries to hurry her into remembering the Gorgon, but she doesn’t respond. Meanwhile, Sarah arrives at the Abbey but fails to get inside; her Sonic Lipstick is broken.

Bea sits talking, explaining that she would give anything to hear her husband’s voice again; no one listens to you when you’re on your own. She sits on her bed, dazed and confused, whilst back at the Abbey Sarah manages to climb over a wall.

In Bannerman Road Maria’s mother arrives at Sarah Jane’s house, finding nobody home. She walks around the house and into the garden, where she sees her fossilised husband in the living room. She makes her way inside, thinking the figure is a statue carved by Sarah. She begins to talk to it, as if it were really her husband. She acknowledges her ability to mess things up for her daughter and former partner, revealing she does miss him more than he realises. She leaves the house, not seeing the tear that rolls down its cold cheek.

As the Sisters continue to chant the portal begins to swell, the alignment is 45%. Sister Helena observes the scene and proclaims, “Soon the Gorgons ad humanity will be one.” Suddenly the bells from the Abbey’s tower ring, Clyde has found a way to distract them. Sure enough Helena sends her fellow Nuns to find the source of the noise and as they do Luke runs it, takes the talisman and dashes out, narrowly avoiding an attack from the Gorgon.

He runs outside to the courtyard where Clyde is waiting. They both flee and find Sarah waiting for them, joining them as the run for the exit. However the Nuns are soon upon them and they find themselves trapped. They are taken back inside and after the talisman is take back to the portal they are locked in the basement, where Sarah explains that she believes that the Abbess isn’t actually the Gorgon. Before she can continue Helena takes her away, leaving Luke and Clyde alone.

Maria upset by not making any progress with Bea and she cries, realising encounters with aliens and the otherworldly only result in being left alone in later life, like Sarah and Bea. Suddenly Bea seems to come round and Maria explains about the Gorgon attacking her father. Bea reveals that she too was once turned to stone, and explains that the talisman returned her to flesh and blood. She tells her that they must get the talisman back and then asks for her mirror, telling Maria to take it with her to the Abbey.

Sarah is brought before the Abbess where the reporter realises that the Gorgons are parasites, life forms that depends on another I order to survive. The last one surviving on Earth is the leader of its race, who will swarm the Earth and take over the human race in order to survive. However it is growing weaker and needs a new host body; Sarah.

Whilst Maria runs with the mirror from Lavender Lawns, in the basement Luke finds a trowel and announces he will use it to make a screwdriver of his own.

Up above them, as the portal continues to swirl, Sarah is tied to a nearby pillar whilst Helena taunts her. Sarah warns her that the Earth will not surrender to the Gorgon, but her captor is not convinced. Down in the basement, Luke uses the trowel to unscrew the lock on their cell door, and he and Clyde leave.

The portal nears opening and Sarah is brought forward to face the Abbess. To prevent her from turning to stone she is blindfolded, and as Helena declares that the Gorgons will bring peace everlasting, the Abbess prepares to relinquish the hold of the Gorgon. Luke and Clyde storm in but are held by two of the nuns, capable only of watching as the Abbess lifts her veil. She releases tendrils of energy from her mouth and eyes, but before they can take hold of Sarah Maria runs in and blocks their path with the mirror. They are rebounded and strike the Abbess, causing her to turn to stone; the Gorgon is dead.

Suddenly Helena and the other Nuns appear to undergo a transformation of the mind, unaware of events unfolding around them; the Gorgon’s hold over them has been severed. Maria approaches the portal and removes the talisman from its place in the stonework. Suddenly the basin drains and the portal closes.

The Gorgon stopped; the four friends then hurriedly return to Sarah’s home. Maria places the talisman around her father’s neck and it returns him to flesh and blood, as it did for Bea. He collapses but is still alive, so the others take him into the garden and wait for him to awaken.

When he does regain consciousness he staggers out onto Bannerman Raod where his ex-wife is waiting for him. Maria also arrives to greet them and apologises for her previous rudeness. Maria’s mother then takes them back to Sarah’s house to show hem the statue she found, but when they arrive it has gone, Sarah proclaiming that she has no idea what her visitor is talking about.

Some time later Maria is forced to bid her mother farewell as she returns to her new boyfriend. She clambers into a taxi and is sped away, but not before telling her daughter to be weary of Sarah Jane.

Maria then joins Sarah up in her attic, where Mr Smith explains that the talisman’s function is to restore distorted human DNA. Maria wonders if it could be used to heal Bea of Alzheimer’s Disease, and she and Sarah return to Lavender Lawns to test the theory out.

Upon arriving they find Bea in her room, humming to herself. Maria greets her but once again she seems not to recognise her. They present her with the talisman and she explains that all the years she owned it she never had the nerve to actually wear it; the one time she did it was with Edgar; the first time he proclaimed his love for her.

She places it around her neck again, and although her illness is not cured she is still given a gift; she hears Edgar’s voice again; telling her that e loves her, and he always will.

Returning to the car Sarah explains that although they may not have cured Bea they have given her peace. Maria asks Sarah if she, like Bea, has found someone to share her experiences with; and she claims that she has…twice.