After rescuing a ship captain, Marn is promised a choice among his three daughters and gives his heart to Clarissa. But a spiteful sorceress twists the lovers into beasts. To free Clarissa, Marn abandons his ocean power and his tail for human legs. When Clarissa and Lucas betray and torment him, he turns to Amphitrite through an ancient treasure. As the spell reverses against its maker, those who wronged Marn realize he may be the only one who can save them.