SS Claridon is an aging transpacific liner days away from being scrapped, and a family’s big move frames its final voyage. Cliff Henderson, [Robert Stack], his wife Laurie Henderson, [Dorothy Malone], and their daughter Jill Henderson, [Tammy Marihugh], plan to relocate to Tokyo and decide to sail aboard the ship, hoping for one last, peaceful journey before their lives change. The mood shifts quickly when a fire breaks out in the boiler room; the blaze is fought, but not before a fuel valve is fused open, setting off a catastrophic blast that rips through the boiler room and blasts a gap in the hull. Chief Engineer Pringle, [Jack Kruschen], is killed in the chaos, and Laurie is trapped under a heavy steel beam in their cabin, her survival riding on a chain of desperate choices.
Cliff charges back through the wreckage to reach Laurie, but she’s trapped on the opposite side of the gaping hole. He discovers Jill on the other side too, and his improvised rescue begins with a makeshift plank that allows Jill to crawl toward safety, while the debris and heat threaten to close the escape routes entirely. Down below, Second Engineer Walsh, [Edmond O'Brien], reports to Captain Adams, [George Sanders], that a bulkhead seam has torn away, further compromising the ship’s integrity. A tense confrontation unfolds as a passenger overhears murmurings and volunteers to help, but the situation remains perilous.
As the situation worsens, Third Officer Osborne, [George Furness], reports that the boiler room is flooding—half full—and the ship starts transmitting an SOS under Adams’s orders, even as he remains reluctant to abandon a vessel he has never lost. Cliff and a handful of men return to their cabins to retrieve tools, hoping to free Laurie, but a cutting torch is required, and the crew scrambles to secure one. The carpenter delivers harrowing news: the boiler room is two-thirds full, intensifying the countdown to disaster. Adams makes a reluctant public announcement for passengers to put on life jackets and begins the grim process of loading and launching lifeboats.
Driven by determination, Cliff locates a torch and races toward Laurie with the help of Hank Lawson, [Woody Strode], but they still lack the crucial acetylene tank. Following Cliff’s instructions, Lawson dispatches Jill to a lifeboat and ventures back to retrieve the needed tank, a dangerous delay that could cost lives. The bulkhead finally gives way, the ship tilts, and a second explosion erupts in the cargo hold, blowing open the bow’s hatch and accelerating the sinking.
In a cruel twist of fate, Adams is killed when the forward smokestack collapses onto his office as he tries to recover the ship’s logbook and papers. Laurie, clutching a shard of a mirror, contemplates ending her own life to spare Cliff the risk of rescuing her, but she ultimately discards the thought and chooses to live. As Walsh concedes that hope may be fading, the team continues to improvise, driven by the will to save Laurie.
The acetylene tank is finally brought back, and the group manages to free Laurie from beneath the steel beam. Water pours into the now-open cargo hatch as Claridon sinks lower, the survivors scrambling toward the stern where a lifeboat waits. Walsh leaps into the sea and swims away, while Cliff, Laurie, Third Officer Osborne, [George Furness], Third Officer Ragland, [Joel Marston], and Lawson push through the rising water to reach the lifeboat. In a final act of solidarity, Cliff helps Lawson aboard, gratitude for his steadfast aid to Laurie’s rescue, as the vessel slips beneath the waves.
> This was the death of the steamship Claridon. This was her last voyage.
