In the highly stratified Atlantis Bay, ruled by apex predators, Winnie, a bottom-dwelling clownfish, is forced to disguise herself as a fragile sea siren in a desperate attempt to win the favor of Harvey, a naive dolphin heir, in order to raise astronomical medical fees for her seriously ill sister, Claire. However, her scheme is seen through by Sean, the pure-blooded orca CEO standing at the very top of the food chain. With the absolute pressure of an apex predator, Sean tests and humiliates her in every way, yet in this ultimate game of hunt, he develops an uncontrollable possessiveness toward this resilient and cunning clownfish.
As Winnie is drawn into the commercial war between the Beluga family and Sean's family, she endures a crippling injury, extortion by thugs, and witnesses Sean risk his life by venturing alone into the Death Trench to save her sister, returning gravely wounded. In desperation
