Life on Mars (2006 - 2007)
If Life on Mars isn't the best tv series of all time it has got to be in the top 5. It's 2006 and Sam Tyler (John Simm) is a police detective on the hunt for a serial killer. He's hit by a car and wakes up in 1973. Has he gone mad? Time traveled? Hallucinated while in a coma? Died and gone to a very strange afterlife? While Sam tries to work out what's happened to him he finds himself a policeman working under Gene Hunt (Philip Glenister), a man of his time (1973). I really don't want to say much more because I'm sure I'll accidentally give away a spoiler. If you haven't watched it you have to. You just have to!
Life on Mars ran for 16 episodes in two series. On American television that's not even enough for a season. The show had ratings and BBC backing that could have kept it on the air for years. Wisely, the producers chose to end the show while it was still at its best. A top show stopping after 16 episodes? That never would have happened in the US any more than the series would work in the US. (Addition: This was proven by the failure of the Americanized version on ABC.)
There's a sequel called Ashes to Ashes that takes place in 1981 with Gene Hunt back minus Sam Tyler. I haven't seen it, but the premise left me a bit cold. It's on DVD (region 2) so I'll have to check it out. Again, crepehanging could make all the difference!