Trust

A body is found on remote wasteland, tortured and executed, and the dead man turns out to be a hit-man. That is the kind of corpse that tells the police they are dealing with the professional end of crime, and the trail leads to Robert Shearer, a local businessman whose fingers are in more than one dirty pie. But the episode has a second agenda, and her name is Kathy Moffat.

Kathy jilted Burke years ago, and she is back, now attached to Frank Morgan, an ambitious MSP she believes is being threatened by Shearer. Burke wants to help her. He goes undercover into a brothel Shearer runs, and the raid that follows catches Burke on CCTV in the wrong place at the wrong time. Chief Superintendent Henson, who has marked him as a dinosaur, takes the excuse with both hands and starts making his professional life miserable. The case widens: three murders link back to Shearer, and Morgan turns out to be less innocent than the picture he presents. And underneath it all sits the quiet question of whether Kathy is using Burke to settle an old score of her own.

Glenn Chandler and Ian Madden wrote and directed. Phyllis Logan is a welcome return as Kathy Moffat, with Alex Norton's Burke at the centre, Blythe Duff's DS Jackie Reid, John Michie's DI Robbie Ross and Colin McCredie's DC Stuart Fraser. Deirdre Davis is Chief Superintendent Henson, Neil McKinven is Frank Morgan, Andrew Townsley is Robert Shearer, Alan McHugh is Assistant Chief Constable David Strathairn and Harry Ward is Sam McIver.

The title says it all: trust is the currency, and everyone in this episode is spending someone else's. The old flame angle could have been sentimental, but the show keeps it sharp, and Henson's campaign against Burke gives the story a villain who never breaks the law. And it leaves Burke standing in the wreckage of his own good intentions, which is exactly where this series likes him.