Greg (Ben Stiller) is already a father of two children. He finally got rid of his old father-in-law who retired from the CIA and was enjoying a happy family life. On Christmas Eve, he received a call from his old father-in-law Jack (Robert DeNiro), who was about to come to his house to visit his grandson. Greg reluctantly received his old father-in-law and his family. At this time, his wife Pam's (Teri Polo) ex-boyfriend Kevin (Owen Wilson) also appeared at their home. Greg couldn't resist Kevin's interference and his father-in-law's disruption. At work, the beautiful and charming female salesperson (Jessica Alba) tried hard to sell him a new aphrodisiac pill, but was accidentally found in his bag by his father-in-law. How will he clean up this mess next?