From the Hugo Award-winning author of "The Rhesus Chart" comes another supernatural case from The Laundry Files... Dominique O Brien her friends call her Mo lives a curious double life with her husband, Bob Howard. To the average civilian, they re boring middle-aged civil servants. But within the labyrinthine secret circles of Her Majesty s Government, they re operatives working for the nation s occult security service known as the Laundry, charged with defending Britain against dark supernatural forces threatening humanity. Unfortunately, one of those supernatural threats has come between Mo and Bob. An antique violin, an Erich Zahn original, made of white human bone, was designed to produce music capable of slaughtering demons. Mo is the custodian of this unholy instrument. It invades her dreams and yearns for the blood of her colleagues and her husband. And despite Mo s proficiency as a world-class violinist, it cannot be controlled "