Season 05 Episode 01

It is 1957. The Cambridge Spring Ball season is under way, and DI Geordie Keating and DC Larry Peters are in a car outside a party, waiting for trouble to start. Will Davenport, in evening dress, is inside the ball at Linley College as the guest of the Newnham students, and Ellie Harding, a reporter on the Cambridge Echo, has taken the nearest telephone box to file copy.

A student is found dead in the water: Jessica, from Newnham, still in the gown she wore at the ball. The pathologist finds she was dead before she entered the river, and Geordie, unwilling to commit, notes she could have struck her head on a rock. Her friend Veronica, known as Vronky, comes forward to say Jess disappeared early in the evening and was not back at the college when the sign-in sheet was completed at 11pm. Leonard Finch, returned from Marrakech with Daniel Marlowe, is finding it hard to live half a life in public, and Daniel settles for a handshake in the street.

Geordie and Will search Jessica's room and find pillows arranged under the bedclothes to look like a sleeper, and a supply of benzedrine. The photograph taken at the end of the ball becomes a document, because it shows Jessica and Vronky together, though Vronky had said she was back at Newnham by 11pm. Daniel develops it and recognises some of the boys. At the men's college they interrupt an assault, two students have been beaten, and the man who threw the punches runs. The pair learn of two rival secret societies: the men have the Berserkers, the women of Newnham the Valkyries, whose initiation involves a red rose at the candidate's door and a swearing-in by candlelight in the garden. Vronky calls the Valkyries a sisterhood and insists nobody in it could have hurt Jessica. The boys admit Jessica and her friend came back to their room after the ball, and one observes that if women want to behave like men they need to learn how men behave. Andrea Shaw, the college's senior fellow, does not object to the societies in principle and confirms that Jessica had no quarrels and no boyfriends, and that caterers and event staff were on the site.

Heather is caught at night apparently about to destroy a box of property and says the items belonged to her boyfriend. A cufflink belonging to the student Matthew Butler's late father connects Matthew to the supply of drugs in the college. Will goes to the party on the night of the second ball, where Vronky asks him to dance and Geordie watches a boy drop a coin into a woman's drink as a tradition. Driving home, Will finds his pocket has been picked, and Vronky has taken the item as proof to the Valkyries that she has slept with a vicar. Heather does not believe her. Will and Geordie find Vronky's room empty and a rose on the door.

Vronky confesses. In flashback she strikes Jessica with a champagne bottle and tips her into the water. Her stated reason is that Jessica left her with the boys, and she was angry because the two were supposed to be a sisterhood and to stand together. Andrea Shaw says Vronky was a victim as well, and the episode leaves the point standing. Vronky is taken into custody and later shown in her cell with a copy of A Room of One's Own.

In the domestic strand, Geordie invites Cathy's mother Diana to move in. Will, who had rowed with his mother Amelia over her plans, goes to apologise, and Amelia tells him she has met someone called St John Gurney-Clifford, who does not use his title, and wants Will to meet him in Norfolk.

The episode is the best of Series 5 and the sharpest the series was about the position of women in the period, because the killing is done by a woman against a woman and the college's senior fellow explains that the societies are harmless because men have had them for centuries. The photograph at the end of the ball breaks the alibi, and the rose on the door is the image the story leaves, since the sisterhood that was supposed to protect Jessica is what killed her.