When CID hears that the dead body of a miner has been found, they are quick to arrive on the scene in the last episode of the award-winning series following time-travelling detective Sam Tyler. They soon discover that a notorious cop killer, Leslie Johns, is behind the murder.

Knowing how big this “collar” could be, Gene Hunt is determined to lead the investigation and beat his new rival, Frank Morgan, to the punch – and he learns that the killing resulted from a fall-out over a planned heist. By going undercover on the heist, CID plan to catch Leslie Johns red-handed but, as usual, A Division are hurried and rash and, inevitably, problems start to arise.

As Sam questions the dubious ethics behind their methods and motives, he meets Morgan in private and what Sam hears turns his world upside down. Suddenly, his reasons for being in A Division are cast in a totally new light – all at once it is unbelievable, yet somehow it makes perfect sense. All Sam has to do, Morgan promises, is one job, then he can “come home” – words that Sam has wanted to hear for so long.

Tuesday 10 April
9.00-10.00pm BBC ONE