Captain Briggs, Arthur Margetson, and Captain Morehead, Clifford McLaglen, are long-time friends who share a voyage dream. Morehead is secretly in love with Sarah Briggs, Shirley Grey, and he brings Briggs to New York to meet her, hoping a proper match might ease the strain between them. But the encounter stirs unexpected feelings: Briggs and Sarah fall for each other, and on the very same day both men propose to her. Sarah chooses Briggs, setting off a dangerous jealousy in Morehead who suspects deceit and fears it could end their friendship.
Briggs confirms his intent to wed Sarah, even if it wrecks the trio’s bond. The couple then plans to sail, but Briggs finds himself short of crew for the voyage. He asks Morehead for help, and the older captain agrees—though his assistance comes with a twists: he sends Volkerk Grot, Herbert Cameron, not to truly aid the ship, and his meddling hints at darker plans. Briggs also enlists a diverse crew, including Anton Lorenzen, Bela Lugosi, a seasoned sailor who has endured much and is teetering on the edge of a breakdown.
As the voyage begins, a murderer stalks the ship, killing crew members one by one while the tension rises. A dire moment arrives when a would-be rapist targets Sarah, and Lorenzen steps in to save her by killing the aggressor—an act that unsettles him deeply, as he sobs over the necessity of murder.
Only a few survive: first mate Toby Bilson, Edmund Willard, Lorenzen, and a third crewman, Ponta Katz, Gunner Moir. The trio confronts a chilling question: who among them is the killer? Katz concludes that Lorenzen would be incapable of such violence, forcing them into a dangerous cat-and-mouse dynamic as they pursue the truth.
Bilson and Katz clash dramatically as suspicion and ambition collide. Katz tries to outpace Bilson, but Bilson shoots Katz and then revels with Lorenzen in a shared dream of seizing control and steering the ship toward a new future. The assault shatters the fragile order, and Lorenzen—who has his own dark past—explodes with anger when he reveals that he was shanghaied six years earlier aboard the same vessel and committed the prior murders to exact revenge. In a swift, brutal sequence, Lorenzen shoots Bilson and hurls him into the sea.
Yet misfortune follows quickly: a stray ship’s boom delivers a brutal blow to Lorenzen, who staggers through the haunted corridors of the vessel, frantic in his search for Bilson. In his fevered flight, he leaps overboard, vanishing into the cold wash of the sea as the ship drifts.
The mystery winds down as the derelict ship drifts until another vessel spots it. The ship is utterly deserted, save for a black cat that prowls the silent deck, a haunting image of abandonment and the echoes of what just occurred.
In a final, grim coda, Morehead is seen discreetly handing money to a crew member and mutters, "I am thinking of Briggs and her, dead!" The curtain falls on a narrative of rivalry, vengeance, and the eerie quiet that follows a ship emptied of its living, leaving only the memory of a love tested by danger and the ghostly reminder of tragedy at sea.
