TV episode review
UK airdate 1 June 2009 (BBC One)

WARNING: Contains spoilers if you haven’t seen the episode!

Alex learns that the past can be changed, and the mole in Gene's team is revealed...

One of the best episodes of any incarnation of the Life on Mars concept blends the timelost detective's quest to go home with a particularly unpleasant detective investigation, and even manages to drop in a bit of Tinker Tailor Soldier Spy, as Gene Hunt sets a trap.

The scenes with the two Martin Summers are shocking enough, particularly after it becomes clear that Alex Drake is wrongly accusing the real 1982 version of being corrupt, and is then potentially framed for his murder. But that's nothing compared to the revelation of Chris Skelton's treachery, brilliantly played by Marshal Lancaster, Keeley Hawes and especially Philip Glenister, whose silence in the interrogation is more powerful than any amount of verbal explosion could be.

One of the most powerful episodes of Dixon of Dock Green saw George Dixon verbally destroy a bent copper, and there's echoes of it here when Gene gives Chris his punishment. The following scenes counterpoint the friendly camaraderie seen at the start of the episode, and you realise just how deeply Chris's betrayal cuts his friends. Even fiancée Shaz can't look him in the eye.

An excellent episode that puts everything in place for an explosive finale. Paul Simpson

VERDICT: 8/10