The revived Sertori family camping holiday is ill-fated not just by choice of location, Mako Island, but in the unfortunate timing of coinciding with the full moon. Cleo's friends tag along to help one another stay out of trouble but Lewis' plans are soon tested when the girls decide to face the powers of the full moon. Meanwhile, Charlotte's discovery of the moon pool at the height of the full moon may have unforeseen consequences.