In this 1979 Italian horror-adventure, a shipwrecked military doctor and a band of convicts find themselves on a remote Caribbean island teeming with danger. While trying to survive, they uncover a bizarre scientific experiment involving amphibious creatures and the ruins of Atlantis. A sinister landowner uses the fishmen for his own gain, while a reclusive scientist and his daughter become unwilling participants in the scheme. With eerie jungle settings, aquatic monsters, and volcanic doom looming, the island hides more than anyone bargained for.