Gwen and Vic are still learning magic and science on the island of Elantya when they learn that Vic's father has finally made it through the crystal doors to Elantya.

But their excitement is short-lived when they and their friends are kidnapped by their underwater enemies and taken beneath the sea. Imprisoned there, forced to witness battles among sea monsters and face the dark sage Azric, they learn of a scheme that could bring Elantya to ruins.

Can they escape in time to save the magical island from destruction?