Hidden, it watched her swimming in the lagoon. It was hideous, bizarre perhaps a throwback to the age of reptiles, perhaps an awful promise of things to come. Suddenly into its steaming domain came the expedition, intrusive, inquisitive, hostile. Afraid but undaunted, the creature tried again and again to destroy the invaders. Nothing stood in its way - except its own inexplicable fascination with Kay Lawrence, the only woman aboard the riverboat Rita. What primitive emotion has caused the monster to spare Kay when others had perished so horribly? And now that it had her in its grip, what did the monster want from her?