Robert McCall, un antiguo agente de la CIA que lleva ahora una vida tranquila, abandona su retiro para ayudar a Teri, que está siendo explotada por la mafia rusa. A pesar de que aseguró no volver a ser violento, contemplar tanta crueldad despertará en Robert un implacable y renovado deseo de justicia.

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.