Hit by a car while investigating a murder, Detective Sam Tyler finds himself transported to 1973 New York, where he helps the homicide squad investigate a killer whose methods are similar to those of the killer he was chasing in 2008.

Still tortured by the turn of events in his life, Sam focuses on a series of fatal robberies, and tries to prove himself to Lt. Hunt and the rest of the squad members.

Hunt is outraged by the murder of a returning Vietnam veteran; Tyler is sent down a mysterious path that might provide clues about his family's past.

Sam's attempt to save a woman under assault pulls him back into his past, where he comes face to face with his mother in 1973.

The brutal murder of a black girl triggers a racial confrontation; Sam battles race attitudes in his own precinct; a dramatic standoff on a rooftop leads to gunshots.

Sam must defuse a hostage situation at County Hospital where a gunman is trying to force a doctor to reverse a dangerous operation on his brother.