A present-day detective is knocked unconscious and wakes to find himself apparently transported back to the 1970s, where he joins a local police unit whose methods are far rougher and less regulated than anything he knows. Struggling to determine whether he is mad, in a coma, or has genuinely travelled through time, he must navigate life in a bygone era whilst searching for a way back to his own. The American remake follows the same premise as the original British series, relocating the action to 1970s New York City.