At long last, Sub-lieutenant Roy Palmer and merchant captain Brian Miller had found the island supply base from which U-boat packs slipped anchor to attack Allied convoys in the South Atlantic.

But, only after they’d been adrift for days with two boatloads of tired, unarmed men. They didn’t even have a radio to pass on the vital news.

What could they do? Not much at all it seemed, until Roy found an ancient cannon and remembered a tale about red hot cannonballs…