From the liner notes

Where were you in 1973? NYPD Detective Sam Tyler (Jason O'Mara) finds himself in the cultural hotbed of New York City in the tumultuous times of the Vietnam War, Watergate, women's lib and the civil and gay rights movements - without a cell phone, computer, PDA or MP3 player -- suddenly hurtled back in time when he's ripped from 2008 after being hit by a car while chasing down a criminal. He's trying mightily to understand what has just happened to him and how he can get back "home."

What exactly is going on here? It's like Sam is on a different planet. It's the Wild West out there: uncontrollable criminals, police on the take... whom can he trust? Forced to use a different moral code and without hi-tech crime fighting techniques, Sam clashes with his new boss at the 125th Precinct, the irascible Lieutenant Gene Hunt (Harvey Keitel), who would rather use his fists than his brains to solve a crime. Hunt, who has earned the adoration of the men under him, does his best to hide his humanity behind a gruff exterior and great gut instincts, in contrast to Sam's more politically correct cutting edge style. But the two begrudgingly combine to make a powerful team -- whether they like it or not.