FBI agent Neville Flynn boards a flight from Honolulu, Hawaii to Los Angeles, escorting a key witness to testify against a mob boss at an upcoming trial. An on-board assassin releases a crate full of hundreds of deadly venomous snakes in an attempt to eliminate the witness. Flynn and a host of frightened passengers and crew must band together to survive the slithery threat.

A university graduate working in the city morgue is able to repeat the same day over again to prevent murders or other disasters.