After having been away for several months, Aquaman returns home to Atlantis. Nearing the capital city of Poseidonis, he finds several dead sentries at an outpost. He also discovers remains of a species of jellyfish that he has never encountered before. At the Atlantean Royal Palace, members of the invasion force reveal their true visage: sentient giant jellyfish. Their plan is to insure the genetic purity of the sea by eradicating all Atlanteans.