McCall believes he has put his mysterious past behind him and dedicated himself to beginning a new, quiet life. But when he meets Teri, a young girl under the control of ultra-violent Russian gangsters, he can’t stand idly by – he has to help her. Armed with hidden skills that allow him to serve vengeance against anyone who would brutalize the helpless, McCall comes out of his self-imposed retirement and finds his desire for justice reawakened. If someone has a problem, if the odds are stacked against them, if they have nowhere else to turn, McCall will help. He is The Equalizer.

To take down South Boston's Irish Mafia, the police send in one of their own to infiltrate the underworld, not realizing the syndicate has done likewise. While an undercover cop curries favor with the mob kingpin, a career criminal rises through the police ranks. But both sides soon discover there's a mole among them.

When the body of her lover washes ashore, a young stripper becomes a prime suspect.