Tycoon John Dexter spears a dolphin-like sea creature off San Blas in the Caribbean. It appears to be dead but, on shore, it comes to life and begins to make shrill, whistling sounds, which have a pattern and can be decoded. On an even more advanced level than the dolphin, the creature has the ability to communicate. To gain world notice, Mercurio, the island's dictator, wants to display it at an international fair he has been staging. But Dexter, whose toughness has become legend, wants to bring his prize back to the U.S. While the two strong men clash, the fish has been able to communicate with his fellow creatures in the sea, and they besiege San Blas in an effort to rescue it.