An old lady called Mrs Randall is scared by the vision of a nun in her bedroom at night in a rest home called Lavender Lawns. Sarah Jane, Clyde and Luke are soon round to investigate. An elderly woman called Mrs Nelson-Stanley tells Luke he is unique and gives him a hidden, mysterious artefact to safely guard.

Maria’s mother temporarily moves back into the family home and upsets her daughter by referring to Sarah Jane and Luke as ‘weirdoes’.

At her place, Sarah Jane uses her computer Mr Smith to run a search on the home. The computer flags up the fact that there’s an alien object in the room - which happens to be the talisman given to Luke by the woman. Mrs Gribbins, the head of Lavender Lawns, visits some nuns and is taken to meet a hooded figure. She screams.

Sarah Jane meets Nelson-Stanley and they discuss the Sontarans and the elderly woman reveals her late husband found the talisman on an archaeological dig. She reveals that the nuns are protecting a Gorgon and mustn’t find it.

Sister Helena - a nun - tracks down Clyde and Luke and demands the talisman. Maria’s dad quickly arrives on the scene and inadvertently scares her off. She soon follows the boys in her hearse and later snatches Luke and takes him to St Agnes Abbey.

Sarah Jane finds out from Clyde where the nuns said they would take Luke, and turns up there posing as a journalist. Maria and Clyde simultaneously snoop around the Abbey and discover Mrs Gribbins - now turned to stone. They are then captured and brought together with Luke and Sarah Jane. Sister Helena says that the talisman will help the Gorgon return to its natural home.

The group returns to Sarah Jane’s home to fetch the talisman and she demands they release Clyde and Luke in return. But a nun flips off the Gorgon’s hood and swipes the talisman. Maria’s dad enters the room and stares at the Gorgon - only for the creature to return the look and turn him into stone.