Keys

Keys turns the investigation inward, where it hurts most. Inspector Kate Longton discovers that one of her own colleagues is a thief, and the episode has to live with the fallout of that. Nobody in the station is above suspicion now, and there is a quiet dread in finding out which desk the dishonesty sits behind. The title is the clue: keys open doors, and somebody on the inside has a set they should not have.

The discovery changes every conversation Longton has. She works the case with Sergeant Joseph Beck, Sergeant George Parrish, PC Brian Kelleher and PC Danny Sparks, while Detective Chief Inspector Mark Perrin (Edward Peel) and Detective Sergeant Dick Maltby (Sebastian Abineri) handle the weight of it. Every colleague becomes a suspect, which is a sentence no inspector wants to think, let alone say. Theft inside a station is a betrayal of trust first and a crime second. The supporting cast supplies the suspects and the bystanders: Jane Downs's Barbara Walker, John Gillett's Roger Greenway and Charles Rea's Harold Flight. The officers do their jobs while measuring each other, and the atmosphere stays taut.

Tony Charles wrote it, Ron Jones directed. Anna Carteret is Kate Longton, with David Ellison as Beck, Noel Collins as Parrish, C.J. Allen as Kelleher, Mark Botham as Sparks, Edward Peel as Perrin, Sebastian Abineri as Dick Maltby, Jane Downs as Barbara Walker, John Gillett as Roger Greenway and Charles Rea as Harold Flight.

The episode's tension comes from the betrayal being small and intimate rather than spectacular. Nobody is robbing banks; the theft is happening at the desks next door. And the show knows that is a harder crime to solve, because the evidence is friendship as much as fingerprints. The reveal, when it comes, is less about surprise than about the damage done on the way there. It is a satisfying hour that makes you watch the station's faces a little harder, the kind that lingers because everyone has worked beside somebody.