Peter McCallister, who is finalizing a divorce from his wife Kate, announces to their children Buzz, Megan and Kevin that he and his wealthy girlfriend Natalie are hosting the visit of a royal family at her mansion, and invites them to spend Christmas there. After the three initially refuse, Kevin accepts the offer after being bullied by Buzz, and revels in the mansion's luxuries and it`s smart remote control system. The next morning, Peter and Natalie go out while Kevin stays with Natalie's butler Mr. Prescott and maid Molly. Kevin notices his old nemesis Marv and his wife Vera scouting the house. After failing to get Mr. Prescott's attention via the intercom, he drives them away by flooding the mansion. When Peter and Natalie return, they do not believe Kevin's explanation, especially since Mr. Prescott claims to have seen nothing. Kevin discovers that the security cameras were turned off during the break-in, leading him to believe that Mr. Prescott is in league with Marv and Vera. To cheer themselves up, Kevin, Peter and Natalie decorate their Christmas tree, although it is later re-trimmed by professional decorators at Natalie's request.