Sarah lies in bed, shivering and remembering the murder. In flashback, she recalls Elena’s twice-weekly visits to her studio for portrait sittings. Elena was affectionate with Sarah’s dog, Flame, and gradually grew comfortable enough to chat and ask personal questions. Sarah remembers teaching Elena what music felt like by having her touch a speaker, then replicating instrumental sounds using tools against her skin: a palette knife for the electric harp, a brush for the flute, a glass jar for synthesized notes. The muller she would later use to kill Elena sat nearby on a shelf throughout these sessions. Sarah justifies the murder to herself as the only way to make Anthony face the truth about destroying her creation.

Havers questions how Sarah could have been at home having breakfast and on the island simultaneously. Lynley explains his theory: Sarah made an earlier trip on foot from Grantchester, killed Elena, ran home to change her blood-spattered clothes, then drove back to Cambridge to discover the body and establish an alibi. She likely wore a wig or scarf to make Elena think she was blonde like Justine. Lynley stops at Fen Causeway, where a cyclist directs them to a posted footpath leading to Grantchester through fields, approximately one and three-quarter miles. Havers times their drive to Grantchester: five minutes and 37 seconds.

Arriving in Grantchester, Lynley spots Anthony’s Citroën in Sarah’s driveway with shotgun cartridges visible inside. He sends St. James to call for armed backup, then he and Havers set off for the house on foot. A local, Norman Davies, confirms Sarah regularly walked to Cambridge across the fields and directs them to the rear footpath. At the house, Lynley pacifies Sarah’s dog and sends Havers away with the animal. He enters through the unlocked back door and approaches the studio, where he overhears Sarah and Anthony arguing. Sarah accuses Anthony of ending their affair to secure the Penford Chair, not for Elena’s sake. Anthony insists he did it for his daughter. Sarah reveals she killed Elena to balance the scales after he destroyed her creation.

Hearing Anthony chamber a round, Lynley bursts into the studio. Anthony fires, hitting Sarah in the arm. As Anthony turns the gun on himself, Lynley tackles him. The gun discharges again as the armed response unit storms in. Anthony gives up, crushing his glasses and declaring that he had to do it for Elena. Sarah is taken away by ambulance with a serious gunshot wound to her right arm. Havers shows Lynley a sketch found on Weaver: a tigress killing a unicorn. Lynley explains that this was Sarah’s confession-La Tigresse, the name given to Whistler’s mistress, represents her while the unicorn represents Elena.

Anthony arrives home after nine o’clock and is met by Justine, who asks about the car and his missing glasses. He tells her the police have the Citroën. Anthony reflects on his marriage to Justine, realizing it was built on superficialities. Ironically, Justine herself had encouraged him to take Sarah’s art class. In flashback, he recalls the night Justine forced him to destroy Sarah’s painting after she discovered their affair. She pressed a kitchen knife into his hand, made him drive to Sarah’s house, and stab the canvas three times while Sarah watched. During the assault, the knife cut Sarah’s hand. Anthony realizes that in destroying the painting, he annihilated Sarah’s most profound expression of compassion and love. He recognizes this destruction as the greatest of his sins against her.

In the present, Justine accuses him of being with Sarah again and breaking his promise to end their affair. Anthony goes to the sitting room and removes his own watercolor paintings from the wall. Despite Justine’s protests, he smashes both framed paintings against the newel post, shattering the glass. He declares he has no art.

Meanwhile, Havers sits in her garden in Acton, reflecting on guilt and the bonds between parent and child. In flashback, she recalls returning home to find her mother in a soiled, catatonic state, neglected by Mrs. Gustafson. Havers calmly fired the woman, then bathed her unresponsive mother and put her to bed. Back in the present, Havers recognizes that judgment, like the decision itself, rests with her alone. She goes inside and telephones Hawthorn Lodge, the care facility in Greenford she had previously visited and speaks to Florene to arrange her mother’s admission to long-term care.

At 11:30 the following morning, Lynley and Havers arrive at St. Stephen’s College to collect his belongings. Lynley reflects that Anthony will likely receive lenient treatment, as his actions will be portrayed as those of a grief-stricken father. He recalls visiting Sarah in the hospital the previous night, where a surgeon told him her arm was saved, but she may never use it again. Havers confirms she took her mother to Greenford that morning and admits she must learn to be alone. Lynley acknowledges that he, too, struggles to let go.

As they leave, they hear a trumpet playing Amazing Grace as Elena’s funeral service concludes. The procession emerges from St. Stephen’s Church, with Anthony, Glyn, and Justine following the coffin. The college porter delivers an envelope to the Master, Terence Cuff, who reads it and quietly speaks to Anthony. Word spreads through the crowd: Anthony has been awarded the University’s Penford Chair in History. Condolences shift to congratulations. Havers asks if Anthony did everything for the Chair. Lynley replies that Anthony himself will likely never know the truth, as confronting the answer would be unbearable.

As they turn into Garret Hostel Lane, Havers makes an excuse about finding a book for a colleague and quickly departs. Lynley sees Lady Helen waiting by his car with a suitcase, realizing Havers left to give them privacy. Lady Helen tells him she wants him to take her home with him. After a moment where she fears she has misjudged the situation, Lynley tells her he still wants her, and nothing has changed. She replies that she was prepared to wait just a bit longer than he had waited for her. They load the suitcases, and as she takes his hand, Lynley feels he is lost.