In World War II, Royal Marine Major Stringer and Captain Thompson chose volunteers for an unknown job. They trained the volunteers intensively in top secrecy for more than a year and then embarked with them on the most dangerous mission of the war - the canoe invasion of an enemy-held French port for the purpose of blowing up giant battleships. The ten "canoe commandoes" were carried to their jump-off point by submarine, despite a depth-charge attack. Facing fantastic hazards, they paddled 70 miles through enemy waters to complete their mission. But only two survivors would return!