A former mobster from New York, having testified against his mafia cohorts, enters the Witness Protection Program and is relocated to a quiet, suburban California town. Renamed to Vincent Antonelli, he struggles to adapt to the mundane, law-abiding life laid out for him, bringing his flamboyant and criminal ways to the clean-cut neighborhood. His love for high-living, coupled with his inability to let go of his old self, leads to a series of comedic misadventures that draw attention, much to the chagrin of the local authorities.

Tasked with keeping Vincent in line is an uptight and overworked FBI agent, who takes his responsibility seriously while battling his own personal issues, including a lackluster marriage. Despite their differences, a unique friendship begins to form between the gangster and the agent as they navigate the idiosyncrasies of suburbia together. Meanwhile, the agent tries to mold Vincent into a respectable citizen, an endeavor complicated by Vincent's irresistible urge to revert to his former lifestyle.