Believing that Zac's unusual behavior is a result of feeling lonely, Evie decides to throw Zac a surprise pool party, against both Cam and Zac's wishes. Because of his being a merman, Zac isolates himself from the party when Lyla tries to console him. After seeing the two together, Evie believes Zac's behavior is the result of him seeing another girl. When Cam hears of this, his frustration with Zac increases and he pushes Zac into the pool, where his secret is "exposed" to the mermaids. Meanwhile, Evie's friend Carly becomes upset when her crush, David, spends all his time with Sirena.