Mikey and Rose are professional assassins. They are also lovers, and once upon a time Rose also knew Mikey's father. During an elaborate hit job for a malicious gangster, Rose fails to kill the main target, the gangster's pregnant girlfriend. Instead, she delivers her baby and convinces Mikey to help her protect them both. As Rose weakens from cancer, Mikey becomes breadwinner for this unusual family. But tranquility will not last.

Steve Martin and Bonnie Hunt return as heads of the Baker family who, while on vacation, find themselves in competition with a rival family of eight children, headed by Eugene Levy,