Henry Reese is under water, literally. He's being given a ride to Mexico in a German submarine still playing the role of Nigel Armstrong, the Brit who was a traitor to his country in exchange for a trunk full of loot. During the ride, he forms an uneasy friendship with Commander Fritz Klein, the Sea Shark. In their conversations, he learns a very disturbing fact about the German war effort and what Hitler is up to now. In the meantime, Helen Meeker and her crew await the arrival of a new team member assigned by the President: a British woman who was to accompany them on a yet to be disclosed mission.