Mia Nicolson is dead. But she does not feel any different- she eats food, gets angry at people, and falls asleep. Aden Constantine is the Collector- he collects the undead and sells them off to the Ministry of the Dead, an organisation that deals with the dead and creatures of the Underworld. But Mia is different. The Ministry, not knowing what to do, orders Aden to keep Mia hostage, learn about her, and update them. As time passes, Aden learns about Mia's powers and the consequences it would have if gone to the wrong hands. Unknowingly, Mia's presence sets terrible events in motion..