The hero of the novel, Leading Seaman Albert Brown, is the sole able-bodied survivor of a sunken Royal Navy warship, who single-handedly delays its attacker, a German cruiser, long enough to ensure its destruction by its pursuers.
It describes his upbringing in late Victorian and Edwardian England, with Agatha as an unmarried mother pretending to be a widow, and her instilling into him a sense of duty to the Navy and to his country.
As the Ziethen was damaged in the exchange, her captain postpones his commerce raiding mission to Australasian waters, and has to find a deserted anchorage to repair his ship.
The resourceful Brown steals a rifle and a small amount of ammunition, water and food, escapes, and makes his way ashore, where he is able to pick off exposed crew members who are trying to repair the ship's damaged hull.
In Forester's description, Resolution Island is an almost-impenetrable tangle of sun-blasted sharp-edged lava blocks covered with cacti, making it extremely difficult for the Germans to locate Brown.
Brown is able to delay the repairs for two days, but is eventually mortally wounded by a lucky rifle shot from a German sailor as the crew is being recalled to the ship.