IOU

Bank clerk Craig Williams is found dead at the greyhound track, and the first irony is that he was due to win. Forty-five grand, which means the race was fixed and the favourite dog nobbled. Craig was the sort of gambler who loses, and on the night he dies he finally wasn't. His huge debts made him an obvious candidate for trouble, but the money he was about to collect points somewhere else. He would have collected it from bookie Niall McShane and his volatile son Ged, which gives both of them a reason to be upset. Then Ged is killed the same way Craig was. And the case stops being simple.

The suspect list spreads out from there: an ex-wife who stood to gain from Craig's life insurance, a married colleague he had a fling with while her husband was abroad, the bookie, the trainer. There are sex tapes in the mix and enough race-fixing to keep a betting shop in business. The second murder changes the shape of the case, and when another suspect dies, the team is racing a father who has decided to take the law into his own hands.

Glenn Chandler and Robert Fraser wrote it, Mike Alexander directed. Richard Rankin is Ged MacShane, Billy McColl is Niall MacShane, Michelle Edwards is Diane Williams, Kelsey O'Keefe is Beth Williams and Vanya Eadie is Charlotte Campbell. Blythe Duff, John Michie, Alex Norton and Colin McCredie do the investigating, with Katrina Bryan's Ellis Sinclair on the pathology.

Greyhound tracks and fixing scandals give the episode a proper Glasgow texture, and the case sprawls in the way these stories should: one small murder, then the whole sordid economy underneath it. The dog track is the perfect setting: everyone there is already backing a lie. The title says it all. Someone was owed, and the debt got collected in blood.