Zac is a teenage boy who decides to camp on Mako Island, unaware that three mermaids, Sirena, Nixie and Lyla, who are guardians of the island, are watching him. That night, when the full moon rises, the boy comes into contact with the magic water of the Moon Pool. The following morning, Zac wakes up discovering he has become a merman with a fish-like tail and the ability to control and manipulate water. His new-found merman abilities will cause problems for the mermaids.　　The three mermaids, curious about living on land, are transformed into humans while in the moon pool during a full moon, now having the ability to live like humans.。猫老师如今很非常地有些不得劲儿。心中一直在嘀咕，若是日后我真的赢了，要怎么办？天地见证，不能耍赖……那是必须要收的！……