Mako: Island of Secrets (2013)

S1E26 Decision Time

Cam deceives Nixie as he harbors ambitions of transforming into a merman and seizing control of Mako. His betrayal shakes their friendship, revealing his true intentions and igniting a fierce conflict between them. As Nixie grapples with the fallout, she must confront the depth of Cam's treachery and decide how to respond to his newfound aspirations for power over their underwater realm.