When David and his brother take a ride in a new boat, their fish finder locates an unusual sea creature near them—it is Nixie taking a swim. As Nixie tries to swim away, David's brother decides to chase it down and discover what the creature is, ignoring David's protests. When Nixie accidentally becomes tangled in a net, she is cornered until Lyla, Sirena, and Zac (believing it is a dolphin), find a way to rescue her.
