The film delves into the true story of Richard Kuklinski, a seemingly ordinary family man living in New Jersey. By day, Kuklinski works as a dubber of pornographic films, but his mundane job masks a chilling secret. Unbeknownst to his loving wife and daughters, he is actually a cold-blooded hitman with a reputation for ruthlessness. Over the years, Kuklinski earns the moniker "The Iceman" for his methodical approach to killing and his method of freezing victims to obscure the time of death. His life becomes a delicate balancing act as he struggles to reconcile his affection for his family with his brutal profession.

Kuklinski's career as a hitman begins to escalate as he becomes increasingly entangled with the mob, specifically the Gambino crime family. His skills are in high demand, leading him to encounter a variety of underworld figures, including a fellow killer named Robert Pronge, who introduces him to more sophisticated methods of dispatching targets. As Kuklinski gets deeper into the criminal world, the stakes get higher, and the FBI begins closing in on the mafia's activities. The tension between his violent job and his role as a family man grows, setting the stage for an inevitable confrontation between his dual lives. Through this, the film explores themes of duality, morality, and the profound impacts of living a life steeped in deception.