In this "half-fish" out-of-water animated adventure, a mermaid princess makes a bargain with a sea witch to become human.

Thor's villainous uncle Loki has escaped Asgard to search for Yggdrasil. The tree holds the power of the Universe. With the help of wolf god Fenrir, Loki plans to destroy the tree and replant it in his image, giving him dominion over all.

When a group of marine biologists crash land in the Bermuda Triangle, they realize they have stumbled into the lost city of Atlantis.