Halloween is an American slasher media franchise that consists of thirteen films, as well as novels, comic books, a video game and other merchandise. The films primarily focus on Michael Myers, who was committed to a sanitarium as a child for the murder of his sister, Judith Myers.

Meanwhile, Dr. Loomis discovers that Laurie is Michael and Judith's sister; she was put up for adoption after the death of their parents, with the records sealed to protect the family. Realizing that Michael has killed one sister and now wants to kill the other, Loomis rushes to the hospital to find them.