Jack Grimaldi is a dirty cop who does favors for the mob in exchange for large fees. He has a loving wife, Natalie, and an adoring mistress, Sheri. He thinks he has it all, until both the cops and mob are outwitted by a vicious Russian mob assassin named Mona Demarkov.
The head of the Italian mob, Don Falcone orders the cop to deal with Demarkov or face dire consequences. Jack is unable to kill Demarkov. Soon Falcone becomes disappointed in Jack's ineptness and orders one of Jack's toes removed. Seriously injured due to the amputation and realizing that he has endangered his wife and mistress, Jack instructs his wife to leave the city immediately, giving her money and instructions where to meet him out West when the time is right. Jack also ends his affair with his mistress and puts her on a train out of the city.
Jack tries to hunt Demarkov but soon realizes that he is putty in her hands. Mona is handcuffed in the back seat of Jack's car, Mona escapes by hooking her legs around his neck, causing him to crash the car, and then slithering out over the front seat and through the shattered windshield without ever freeing her hands; the effect is simply terrifying. Jack is attracted to her sexually and no match for her professionally. Mona offers to pay Jack to help her eliminate Falcone and fake her own death. Although he obtains phony papers for her, she refuses to pay and attempts to strangle him; he shoots and seriously wounds her, but she escapes. Mona lures Jack to an abandoned warehouse, where he attempts to kill her but manages to shoot Sheri instead. Mona fixes the corpse so as to suggest that it was she, and not Sheri, who died (her scheme involves severing her own arm and substituting it for Sheri's). Mona handcuffs Jack to the bed and has her way with him in menacing S&M gear--but only after unbuckling her new prosthetic arm, her last concession to conventional appearances. Demarkov tricks Jack into killing his mistress and then forces him to kill Don Falcone, even after losing the use of her arm and having it replaced with a prosthetic. In the end, Demarkov turns Jack into the police, his former associates, and cops a plea deal that will indict Jack for the multiple murders that she tricked Jack into doing