Aquata Returns

S1 E21: Sirena's sister Aquata returns to Mako with wonderful news - Sirena can return to the pod! Unfortunately, the invitation isn't extended to Lyla and Nixie. When Zac finds the Moon Pool he tries to kick Lyla and Nixie out. In a showdown between Zac and the mermaids, Lyla manages to seize the Trident from Zac, and hides it in a cave deep in the ocean. Sirena decides to stay and defend the island, and the Moon Pool, with Lyla and Nixie.