No Other Love, aka Love Me Tender

The season's final case is the one that breaks Frost. It begins with two investigations and ends with a coffin. First, the elderly Olive Walters murders her husband Harry — an impulsive act born of decades of emotional abuse, of a marriage in which he refused to take their two-year-old daughter to hospital nearly forty years ago, letting her die of a fever. Olive is released; she dies soon after, of natural causes, her one act of violence standing as her only liberation.

The second case is a robbery at Peter Lawson's pawn shop — but the robbery is a mask. Peter's teenage daughter Rachel is the victim of sexual abuse, and her brother Matthew robbed their father to pay for the journey to their elder sister Joanna in Blackpool, where Rachel could end the pregnancy. Joanna, abused herself, is terrified the youngest sister Suzanne will be next. When Peter is murdered, the children seem obvious suspects — until the truth surfaces: their grandfather Charlie, the family patriarch, killed Peter to hide the truth that he had long been abusing his own granddaughters. Confronted, Charlie holds Frost at gunpoint — and Clive Barnard, Frost's oldest friend and partner, dies shielding him. Charlie turns the gun on himself.

Frost is annihilated. He tenders his resignation, and places his George Cross medal in Barnard's coffin, declaring the man who died for him a true hero — an act of grief that says everything about how Frost measures himself against the people he loves.

No Other Love, written by Sian Orrells and directed by David Reynolds, is a devastating episode about the poison that families keep secret — abuse, complicity, the violence of fathers — and it pays off the Barnard character with the series' most brutal death. Anthony Bate's Charlie, pious and monstrous, is the face of the show's darkest theme: the monsters are never strangers, and they are never far from home.

The one where the series breaks its own heart: a family's secret poison, a partner's death, and a hero who measures himself against the man who died for him. The episode where the series breaks its own heart.