Sabrina (Hart) and Gwen (Strong) head for the Great Barrier Reef to study marine biology. It is here in picturesque Down Under that the teenage witch meets a handsome "merman", Barnaby (Scott Michaelson), who has become ill due to human environmental pollution. Sabrina takes up the ecological cause on behalf of all the inhabitants of the sea in this let’s-make-the-world-a-better-place movie, and fights to save the last mermaid colony from destruction.