Jenny Cavanaugh, the ghostly lady of 926 Augur Lane, has enlisted the services of her detective-agency tenants to solve a decade-old murder--her own. Abigail Rook and her eccentric employer, R. F. Jackaby, dive into the cold case, starting with a search for Jenny's fiancé, who went missing the night she died. But when a new, gruesome murder closely mirrors the events of ten years prior, Abigail and Jackaby realize that Jenny's case isn't so cold after all. Soon Abigail's race to unravel the mystery leads her down to the mythical underworld and deep into her colleagues' grim histories to battle the most deadly foe she has ever faced.