Monsters and madmen and murderers, oh my! A club of serial killers calling themselves Oz is stalking the streets of London. Alone and desperate, 17-year-old Halo finds herself drawn into the middle of their blood-soaked storm of murders. Struggling to survive, Halo must contend with both known and unknown killers, put her trust in the most unlikely of devilish places, and play by a new set of rules if she is to become the Assassin of Oz. Gavin, a young US homicide detective, has moved to the UK to catch the serial killers, Tin Man, Lion, Scarecrow, and The Munchkin Masher but soon finds himself two steps behind the headline-grabbing murderers and one step behind vigilante group, Wonderland. Stalked by death and danger, both Halo and Gavin are going to need all the brains, heart, and courage they can muster to take down Oz.