The son of a virtual world designer goes looking for his father and ends up inside the digital world that his father designed. He meets his father's corrupted creation and a unique ally who was born inside the digital world.

Two years after the events of the first film, Larry Daley, former night guard at the American Museum of Natural History, now runs his own direct response television company that sells inventions based on his experiences. He travels to the museum, discovering most of the exhibits will be moved to the Federal Archives at the Smithsonian Institution and replaced with holographic information providers. The Tablet of Ahkmenrah is to remain in the museum, leaving most of the exhibits without the ability to come to life at night. After the exhibits are moved, Larry receives a phone call from Jedediah, who informs him that Dexter the monkey stole the tablet and took it to the Smithsonian, bringing every exhibit in it to life. Larry travels to Washington, DC, navigating his way to the archives with help from his son Nick while posing as a night guard.

On , Laurie Strode accidentally kills a paramedic with whom her brother Michael Myers (Halloween) had swapped clothes. A guilt-ridden Laurie becomes an inmate at the Grace Andersen Sanitarium, where the nurses believe her to be catatonic. Instead, she is preparing for Michael's return. Three years later, on October 31, 2001, Laurie, pretending to be heavily medicated, prepares herself for the inevitable confrontation with her brother. Michael breaches the facility and kills two security guards, as he makes his way to Laurie. After a chase, Laurie lures Michael on to the institution's rooftop. Although he falls into her trap, Laurie's fears of again killing the wrong person get the better of her; when she tries to remove his mask, Michael kills Laurie by stabbing her and throwing her off the roof. Michael returns home to his abandoned childhood house.