The Perseus Survivor documents the story of British Navy stoker John Capes, the lone survivor of a sunken submarine who hid from enemy forces for 18 months before his rescue. The Perseus, a British Parthian-class vessel built in 1929, was sunk by depth charges dropped from an Italian ship during a mission. On the submarine was a crew of 59 plus two passengers, one of whom was 31-year-old Navy stoker John Hawtrey Capes. When the sub sank, Capes washed up on the shore of Kefalonia, and for 18 months he hid behind enemy lines, hoping for a rescue that might never come.