Five vacationers and two crewmen become stranded on a tropical island near the equator. The island has little edible food for them to use as they try to live in a fungus covered hulk while repairing Kessei's yacht. Eventually they struggle over the food rations which were left behind by the former crew. Soon they discover something unfriendly there...
Ryutaro is a spy employed by the shogun Tokugawa Iemitsu, who is the target of assassination attempts that aim to hand power over to his younger brother Tadanaga.
Intelligence director Suritai asks agent Kitami to steal money from anti-government guerrillas.
