 Cassandra, a resident of Atlantis, has dreams of it being destroyed and a mysterious man saving her. When she finds a shipwrecked Hercules on the beach, she recognizes him as the man from her dreams. Hercules convinces her to warn the other Atlanteans of impending disaster, but they refuse to believe her; Hercules is sent to be killed while the king tries to force Cassandra to tell him how Atlantis will be destroyed. Hercules escapes (of course), frees his captured shipmates, and hunts for Cassandra.