When a water-tight court case fails to put away a local gangster, Gene Hunt won’t let it drop, as the series following time-travelling detective Sam Tyler continues.

Eager to see a guilty man behind bars, Sam helps Gene with his enquiries. They are soon led to washed-up boxer Davie Mackay, a man who once loved his sport passionately but is now jaded by the industry’s underground criminal activities.

Unable to cope with a guilty man walking free earlier that day, Gene turns to alcohol for comfort but soon lands himself in a spot of bother. When it appears Gene may have killed someone, it’s up to golden boy DI Sam Tyler, and the rest of the CID unit, to help him out.

In order to ensure a clean case, DCI Frank Morgan is sent from internal affairs to investigate A Division’s methods of policing. Morgan is a man intent on doing the internal investigation by the book – so thoroughly, in fact, that Sam can’t help but be impressed by his methods and his appealingly modern approach. Sam starts to accept that the evidence is stacking up against Gene and, as it becomes harder for the team to prove his innocence, even Gene’s loyal protégé, Ray, starts to have doubts.

However, Sam redoubles his efforts to prove Hunt’s innocence, if only to preserve the fragile world he has existed in. But the investigation eventually comes to a shocking conclusion – one that rocks the very foundations of his world.

Tuesday 3 April
9.00-10.00pm BBC ONE