1953. Buck, Sonny and Tumb have been sent to the Patuxent River Flight Test Centre to help design and test the Sea Dart, a seaplane jet. Meanwhile, a former SS general previously in command of Nazi special projects, Hans Kammler, has been spotted in Argentina by an American agent - who is then promptly murdered along with every member of the local CIA network. The task of locating a potential secret Nazi base then falls to Buck, his friends ... and the Sea Dart.