Basking in the warmth of an Indian summer, the British Military in Germany hold an Open Day to ease the stress of constant movements of personnel to and from war zones. Entertainments include medieval knights, jousting, and, for children, a diver in a water tank fighting synthetic oceanic monsters. At midnight, guards discover a body in the tank with the tentacles of a lifelike jellyfish wound tightly around his throat. Captain Max Rydal, wrestling with personal problems, is faced with a bizarre collection of clues as he investigates the crime.

Genre: Mystery