Fugitives from the very Guild they once served, scholar Edwin Blackthorn and his guardian Julian Thorne are out of time. Their only lead on the elusive Magister Rowan is a cryptic invitation to a lavish Fae masquerade where London's elite are being replaced by soulless duplicates.

But the ball is an elaborate trap, and Edwin is the prize. Dragged through a portal to the deadly Fae Wylds, he becomes a sacrifice in an ancient war. To get him back, Julian must follow, armed with little more than a reckless vow. In a kingdom of illusions, they must trust each other completely to unmask a queen, shatter a realm, and find the one final truth that will either end their war or end them for good.