Harley has a game plan to stop the third ritual: infiltrate the Cult of Eris and steal back her mother's soul. But her only way in is through her devious half-brother Finch, the same guy who was Katherine's most devoted bootlicker not too long ago. Left with no choice but to break Finch out of prison, Harley must play the part of a loyal cultist. Within Katherine's inner circle, deadly initiation trials and watchful enemies make every moment a battle for survival. Harley hasn't forgotten that Finch once belonged to the cult himself, and she wonders if she'll end up with a valuable new ally or a knife in the back.