A yacht comes perilously close to colliding with a swamped, dismasted, derelict vessel; only the captain's instincts prevent the crash, as he sees a flash of light in the darkness. The source of the light cannot be found, but the yacht's spotlight picks out the derelict. Investigating the vessel, the crew of the yacht decides to tow it, in order to collect money for salvage. They arrange a tow-line, and leave a skeleton crew of four volunteers, together with the bo'sun, aboard. A little later, the captain of the yacht is shocked to discover that the towline is no longer connected and the ship is a considerable distance from the yacht. The crewmen aboard the vessel are gone.