Ep 7. Moon Spell

Emma is nervous about an upcoming test and decides to stay up all night studying, unaware that tonight is a full moon. Meanwhile, Cleo is worried about her little sister Kim who is spending too much time with Sam, a known troublemaker. Rikki, annoyed that Emma is ignoring them, goes to Mako Island where the full moon causes the three girls to undergo a transformation - into mermaids. Back at school the next day, Emma is still studying and begins to feel the effects of the full moon. Lindsey, the new girl at school, offers to tutor Emma and suggests they meet in the evening at her house. Emma, still feeling the effects of the moon spell, realizes too late that she has been lured into a trap. Lindsey and her friends have set a trap for Emma and plan to use her for their own gains. When the other girls discover Emma is missing, they frantically search for her and quickly realize the danger she is in. Now the girls must work together - using their mermaid powers - to rescue Emma from the clutches of Lindsey and her friends before it's too late.