In this sequel to the Nebula Award-nominated and Tiptree Award Honor Book that New York Times bestselling author Seanan McGuire called "exciting, inventive, and brilliantly plotted," Millie unwillingly returns to the Arcadia Project when an impossible and deadly situation pulls her back in.

Four months ago, Millie left the Arcadia Project after losing her partner Teo to the lethal magic of an Unseelie fey countess. Now, in a final visit to the scene of the crime, Millie and her former boss Caryl encounter Teo's tormented ghost. But there's one problem: according to Caryl, ghosts...