Bob Ho (Jackie Chan) is an undercover CIA superspy who decides to give up his career in espionage to settle down with his next-door neighbour and girlfriend, Gillian (Amber Valletta). But Bob has one more mission to complete before Gillian agrees to marry him: winning over her three opinionated kids.

When Gillian suddenly has to leave town, Bob volunteers to babysit the children so he can earn their approval. But when one of the kids mistakenly downloads a top-secret formula from his computer, Bob's archenemy, a Russian terrorist, moves in for the attack, forcing Bob to juggle the roles of spy and prospective stepfather in the most challenging mission of his career!