The story 1943 - the Pacific War. U.S. Submarine 'Shark' is gliding through enemy waters on a dangerous mission. Ken Braden, young officer just out of the Underwater Demolition School, has to swim ashore to a Jap-held island, photograph a code and get back to the patrolling sub. - without detection. This is one of the most exciting sea-stories of all time, written by a man who knows all about action.