MacKayla Lane and Jericho Barrons return in the epic conclusion to the Fever series, where a world thrown into chaos grows more treacherous at every turn. As Mac, Barrons, Ryodan, and Jada struggle to restore control, enemies become allies, and the lines between life and death, lust and love, blur. Black holes threaten Dublin, and the greatest danger is the one MacKayla Lane has unleashed from within: The Sinsar Dubh—a sentient book of evil—has possessed her body and seeks power relentlessly. The fate of Man and Fae depends on destroying the book and recovering the long-lost Song of Making, the only magic that can mend the earth. To succeed, sidhe-seers, the Nine, Seelie, and Unseelie must forge unlikely alliances and make painful choices. Barrons and Jada's mission includes finding the Seelie queen to harness the song's power, negotiating with a lethal Unseelie prince aiming for dominion, and figuring out how to destroy the Sinsar Dubh while keeping Mac alive.