Mike Enslin is a writer who is known for writing books on the paranormal. He frequently checks into hotel rooms thought to be haunted, but none of them really are. One day, after a book signing in which he states that he doesn't believe in the paranormal, he is involved in a surfing accident, but recovers and receives a strange postcard in the mail. It shows the infamous Dolphin Hotel, and dares him to visit the mysterious Room 1408.
Mike tries to be allowed into 1408, but is refused over the phone. He calls his friend, who informs him that if the room is empty, the hotel has to let him in. The manager, Gerald Olin, attempts to dissuade Mike from checking in, showing him a case file of stories about people who have died or went insane in the room mysteriously. He even attempts to bribe Mike against it with a large bottle of cognac. Mike accepts it, but still refuses to leave. Olin allows him the room keys very reluctantly.
Mike hears the radio in Room 1408 come on by itself and play the song "We've Only Just Begun", but he dismisses it as Olin attempting to trick him. He approaches the window, and when he turns around, his previously unmade bed and uncleaned room are made and cleaned. He runs around the room to catch somebody trying to fool him, but finds nobody. At 8:07, the song plays again, and the clock resets itself to "60:00". The window slams down on Mike's hand, and when he shouts angrily over the phone, the operater speaks of food that Mike did not order. He begins to see hallucinations of "victims" who had stayed at the room in the past, and attempts to leave Room 1408, only for the doorknob to break from the door, trapping him.
Via laptop, he contacts his wife Lily, but the sprinkler system then shorts out his laptop before he can finish talking to her. The room tempature falls to subzero and his laptop begins to work again. Lily informs him that the police have arrived at 1408 to find it empty. A clone of Mike appears in the chat window and urges Lily to go to the Dolphin Hotel herself; she relents and begins to travel there. A picture of a ship then breaks open, flooding the room. Mike awakens on the beach, and it appears that he was only dreaming. He reconciles his relationship with Lily, and the rest of his family, including his father.
Mike writes a book about his "dream", but at the publisher's office, the walls are torn down to reveal that Mike is still in Room 1408. The room is now burnt and falling apart. A vision of his deceased daughter Katie appears to him, and he embraces her until she crumbles into dust. He finds the clock radio in the rubble and sees that the clock has reset itself again, forcing him to either relive the whole night for all eternity or die on a noose. He refuses either option and uses the cognac to set the now-fully-restored room on fire.
After that, two endings can be viewed. The original ending was not released in theatres but is viewed by most people as better, while the used ending is usually viewed.
- John Cusack as Mike Enslin
- Samuel L. Jackson as Gerald Olin
- Mary McCormack as Lily Enslin
- Tony Shalhoub as Sam Farrell
- Len Cariou as Mike's father
- Jasmine Jessica Anthony as Katie Enslin
- Isiah Whitlock, Jr. as Hotel Engineer
- Kim Thomson as Hotel Desk Clerk
- Benny Urquidez as Claw Hammer Maniac