รายละเอียด(อย่างย่อ) Larry Daley is a divorced man from Brooklyn, hoping to find a good job to impress his ten-year-old son Nick, but his ex-wife Erica believes he is a bad example for their son. Larry is hired at the American Museum of Natural History to replace the retiring security guards Cecil Fredericks, Gus, and Reginald. Larry meets the museum's neurotic curator Dr. McPhee, and very attractive museum docent Rebecca Hutman, who plans to write a dissertation on Sacagawea. On his first night, Cecil hands Larry an instruction manual on what to do in the museum, warning him not to let anything "in or out."