The SS Claridon is an old ship that is scheduled to be scrapped after just a few more voyages. Cliff (Stack) and Laurie Henderson (Malone), alongside their daughter, Jill (Tammy Marihugh), are relocating to Tokyo and decide to sail there on board the ship. A fire in the boiler room is extinguished, but not before a boiler fuel supply valve is fused open. Before the Chief Engineer can manually open a steam relief valve, a huge explosion rips through the boiler room and the many decks situated above it, killing him and some of the passengers and trapping Laurie under a steel beam in their state room, in addition to opening a huge hole in the side of the ship. From then on, it's up to her husband and a crewman to cut her free before the ship goes under.
This film features examples of:
- Fight to Survive: The SS Claridon suffers a boiler explosion that damages the ship so much that it begins to sink. One passenger is trapped in her cabin by a falling beam and her husband and a crewman must cut her free before the ship goes under.
- The Last Title: The Last Voyage.
- Trash the Set: The reason the movie has such realistic effects of the cruise ship sinking is simple: the producers really did sink a ship.
- What Happened to the Mouse?: The last scene of the plucky Second Engineer Walsh - a fairly important character in the story - is jumping overboard and swimming away when the ship enters its final death throes.