Jack initially comes across as a loving father, but spending time in the Overlook Hotel affects him adversely; he becomes increasingly frustrated and violent. He also becomes very hot-tempered and deranged until he loses himself completely; it is his lack of sanity that eventually leads to his demise.
In the film, Jack, his wife Wendy, and their son Danny, go to the Overlook Hotel in Colorado, which is closed from October to May, so Jack can apply for the position of winter caretaker. He plans to use the peace and quiet of the hotel to work on his newest novel. The manager of the hotel, Stuart Ullman, warns Jack that a previous caretaker, Charles Grady, went berserk and killed his family before killing himself. Jack brushes this off, believing nothing bad is going to happen.
As a month goes by, Jack makes little progress on his novel, and becomes increasingly frustrated. Meanwhile, Danny has frightening visions and senses an evil presence is lurking within the hotel, and after Danny is attacked by a ghostly woman in a forbidden room, Room 237, Jack has a nightmare where he believes he killed his wife and son. He goes to the hotel's Gold Room, where Lloyd, a ghostly bartender, serves him Bourbon Whiskey. After he is told about Danny being attacked in Room 237, Jack goes to check it out, and finds the ghostly woman, but insists he saw nothing. Wendy feels that they should leave the hotel because of Danny's condition. Jack angrily goes back to the Gold Room and meets with Grady's ghost.
As Wendy looks for Jack, she discovers he has been repetitively typing "All work and no play makes Jack a dull boy." Jack suddenly appears and threatens her as she voices her thoughts that Danny should be taken to a doctor, demanding to know if she ever considered his responsibilities and if she is even concerned about him. She knocks him out with a baseball bat. She drags him to the kitchen, into the pantry; he regains consciousness just as she locks him in the pantry. He begs her to let him out, and complains that he's badly hurt. Wendy tells him that she's going to use the snowcat to bring a doctor to him. Jack maniacally tells her that she's going nowhere, for he disabled the snowcat and the two-way radio.
Later, Jack talks with Grady again, who tells him he must eliminate his wife and son, before releasing him from the pantry. After Danny writes "REDRUM" (which is "MURDER" spelled backwards) and chants the word, waking Wendy, Jack begins attacking the door to their quarters with an axe. Wendy and Danny hide in the bathroom, and attempt to escape through the window, but only Danny can get through. Jack chops a hole in the bathroom door, saying "Heeeere's Johnny!", and attempts to unlock it, but Wendy slashes his hand with a knife. He then hears Dick Hallorran, the chef, arrive in a snowcat and leaves the room. In the lobby, Jack ambushes and strikes Hallorran with the axe, killing him. Danny, who was hiding in a cabinet, screams after witnessing the massacre, getting Jack's attention. Danny runs into the hotel's hedge maze, with Jack chasing him. Luckily, Danny cleverly lays a false trail to mislead Jack and hides in a side path. After Jack hastily wanders down another path, Danny runs back in his own footprints to escape from the maze. Meeting up with Wendy outside, the two escape using Hallorran's snowcat. Hearing the engine, Jack calls out to Wendy unintelligibly. Eventually, Jack grows exhausted and sits down to rest, freezing to death.