Larry Daley is now CEO of Daley Devices, a direct response television company that sells inventions inspired by his experiences as a night security guard at the American Museum of Natural History. Larry returns to the museum, he finds out that it is closed for renovations and upgrades. Night has fallen upon the Smithsonian Institution in Washington, DC… yet something incredible is stirring as former night guard Larry Daley finds himself lured into his biggest, most imagination-boggling adventure yet.