After the decline in Atlantean culture following the sinking, Kida, now Queen and married to Milo Thatch, is using the heart of Atlantis to restore her city's former glory. Suddenly, Milo's comrades and Mr. Whitmore arrive in Atlantis; while their arrival is unexpected, the Atlanteans welcome their old friends. Unfortunately, they have come to inform them of a mysterious creature causing trouble on the surface.