Freelance journalist Martyr is sent to Gorgona Island by his publisher, where rumors about a huge flow and concentration of jellyfish on site are capturing Influential Authorities' attention. While Gorgona officials welcome Martyr by shooting at him (access to the island is banned due to the presence of a penal colony), two beautiful women, Doctor Julia Bonnie Wogecrasher and Professor Froggy Dauphine, reach the island through synchronized swimming underwater, covering twenty nautical miles. The three of them, who establish a relationship in the days to follow, come across unsettling facts about Gorgona, and Commander Segevarje is involved too (management director of the frogmen, who discretely patrol the Tuscan Archipelago): the latter, always wearing a diving mask and snorkel to hide his identity, reports a terrible occurrence has happened on the island, because of which a few males were turned into stone. Was it the jellyfish... or Medusa herself ? In a smooth and gripping succession of twists and turns, Gorgona Island is the scene of a power and drug scheme which, once more, leads beyond the author's fine eroticism and jaunty irony.