Evie, Zac's girlfriend, starts to feel threatened by Zac's growing closeness to Lyla and begins to wonder if she's losing Zac's attention. As tensions rise, Zac must navigate his relationships with his friends and family while trying to achieve his goal.

As Zac tries to help his school win, he begins to develop feelings for Lyla, who seems to be hiding a secret. Meanwhile, Ondina and Weilan are trying to help Zac with his campaign, but their efforts only lead to more chaos.

In Season 4, Episode 16 of Mako Mermaids, titled "The Top", Zac's friends and family are preparing for the annual Mermaid Bay Top School Awards. Zac is determined to help Mermaid Bay Elementary win the top award, but things get complicated when he realizes that Lyla, a rival school's student, is also competing.