Due to his outstanding performance as a guard at the New York Museum of Natural History, Larry (Ben Stiller) became the CEO of a small home appliance company, and was interviewed by a famous talk show host on TV. His son admired him, and his love was always with him, and he looked very proud. However, the good times did not last long. When he revisited the old place, he unexpectedly found that the curator had updated the exhibition and was preparing to move the outdated exhibits to the Smithsonian Museum in Washington for continued exhibition. This made Larry feel a little angry. He felt that he had the responsibility to revive the glory of the museum, so he decided to stay as a guard for another night to arouse the joint efforts of those old friends. In fact, after dealing with Roosevelt (Robin Williams), Lincoln, Napoleon, Ivan the Terrible and Al Capone, he encountered a strong enemy-the evil ancient Egyptian pharaoh Carmen La, and the two staged a thrilling duel in the museum again at night...