When she discovers that a would-be creator is determined to make his (or her) own demons and needs her blood, former witch-turned-day-walking-demon Rachel Morgan, a bounty hunter, faces her toughest adversary yet --humanity.

A tale set in an alternate-universe, post-World War II era finds precarious peace agreements between England and the USSR threatened by the murders of warlocks responsible for safeguarding British national security, a situation that falls into the hands of two supernaturally enhanced siblings and a former spy who would protect the queen.