Mina, an agent of industrial espionage, is hired to investigate the secretive hidden project of a powerful industrialist. Following the trail to Project Charybdis, she finds an underwater world where female slaves serve the lusts of others, unable to escape as they are transformed into latex-bound mermaids, pets, and objects of carnal excess. Some are paid to be present, others are captives who have been abducted and forcibly trained to serve. Having blundered into the project, Mina joins the rubber-encased ranks of the deep-sea harem. There she finds new pleasure in her strict captivity as she surrenders herself to those she had been sent to expose, and who now subject her to endless and ingenious acts of depravity.