Hunters have targeted the Merfolk for over a hundred years. Forced into hiding, the Sirens discover that their biggest threat may very well be their own kind. Sirena, as the last known royal Siren, must battle her fears and doubts to restore the sanctity of the oceans. What Sirena doesn't realize is that the greatest danger to the merpeople comes from within their own ranks. When the undead mermaids rise from their territory and threaten harm to the living, Sirena and her pod must fight to save one another and the rest of their merpeople.