Luck turns against Standing (Dennis Waterman) when he loses a poker game, owing bookie Michael Jacobs (Kieran O'Brien) £10,000.
But Michael offers him a chance to clear his debt by finding out what happened to his dad Joe, who died after being mugged outside Walthamstow stadium in 1983.
Although UCOS is investigating the case of Stanley Ackerman, whose wife is mounting a noisy protest outside police HQ, Standing persuades Lane (Alun Armstrong) to help him dig into Joe Jacobs' death secretly.
They go to the dog races and talk to Joe's brother Peter (Philip Whitchurch). Pullman (Amanda Redman) and Halford (James Bolam) follow, feeling left out, but when Pullman hears about the case she agrees to pursue it quietly...
Lane finds a diary hidden in Joe's desk, containing references to Bomber Boyo, a champion greyhound stolen in the early 80s. The diary charts his stud record since then, showing which dogs he fathered. Also inside the diary is a hand-drawn treasure map.
It looks like Joe was on to a money-making deal that went wrong. Standing seeks out Emma Winters (Gillian Taylforth), who worked at Bomber Boyo's kennels before becoming one of the top breeders and trainers in the game. There's a spark between them and Standing visits her farmhouse, where a stuffed greyhound is on display among dozens of photographs.
Lane finds the location of the map and the team meet there at dawn. They dig up a dog skull with a bullet hole in it. If it's Bomber Boyo, DNA from the dogs named in Joe's book will prove it. But when a story about police digging up dead dogs is leaked to the papers Strickland (Anthony Calf) goes ballistic.
Desperate to restore her credibility, Pullman visits Michael, only to find out about his gambling deal with Standing. With the odds stacked against them, the squad must pull together to find Joe's killer - and uncover the real story of Bomber Boyo's disappearance.
