A German sub destroys a rowboat, a buoy, and another German sub (obviously, not the pride of the fleet). Meanwhile, Popeye, with a boat full of "spinach fer Britain", rams into the sub by accident. The sub cuts Popeye's ship in half with machine-gun fire, separating him from the spinach; it then sends a torpedo into the remains, which Popeye collects in a rowboat. Popeye spins the sub upside down, then ends up in a mine field (again barely saving the spinach). After another run-in, the spinach lands in the sub, and Popeye ends up underwater, where he opens his own can and smashes the Nazis into the mine field. He rows the sub full of spinach into the fog and, ultimately, right to #10 Downing Street.