The King of Atlantis is enraged as another non-pureblood child, or 'mudblood', is born. He demands the culling of all impure children and their mothers, desperate to find a pure 'godblood' who can awaken Poseidon's power before a barrier collapses and dooms Atlantis. Meanwhile, Princess Rosalie reveals she is secretly a mudblood, hidden by her mother who cast a life-draining dark magic to disguise her as nobility. Now married to a godblood, Rosalie's greatest fear is realized as her mother's protective spell fails on the day she gives birth, exposing her true lineage.