After getting involved in a mysterious road accident in 2006 and losing consciousness, DCI Sam Tyler awakens in 1973 to find himself a DI assigned to investigate a series of murders.
In season 2, Sam is haunted by visions warning him of a danger threatening him. At the same time, he encounters a young version of a murderer from the 21st century who Sam helped to arrest, but he is convinced that the criminal escaped punishment and returned through time to take revenge.