'A blood-pumping, nerve-shredding thriller . . . ingenious'br(A. J. Finn, author of The Woman in the Window)brbr'Breathtaking'br(Daily Mail)brbr'Wildly entertaining . . . truly frightening'br(New York Times)brbrbrHow do you find a killer when you're surrounded by madness?brbr1935. As Europe prepares itself for a calamitous war, six homicidal lunatics - the so-called 'Devil's Six' - are confined in a remote castle asylum in rural Czechoslovakia. Each patient has their own dark story to tell and Dr Viktor Kosárek, a young psychiatrist using revolutionary techniques, is tasked with unlocking their murderous secrets. brbrAt the same time, a terrifying killer known as 'Leather Apron' is butchering victims across Prague. Successfully eluding capture, it would seem his depraved crimes are committed by the Devil himself.brMaybe they are... and what links him with the insane inmates of the Castle of the Eagles?brbrOnly the Devil knows. And it is up to Viktor to find out.brbr'Deep, dark, and twisty . . . a gripping masterpiece of a thriller!' Alex Grecian, New York Times bestselling author of The Yardbrbr'Elegant, edgy, ingenious' A. J. Finn, New York Times bestselling author of The Woman in the Windowbrbr'Drags you into its dark world kicking and screaming . . . gets under your skin slowly, then goes deep, like the tip of a butcher knife' New York Timesbrbr'Sensational . . . twists are jaw-dropping . . . a mind-blowing story line that will appeal to fans of Caleb Carr and Thomas Harris' Publishers Weeklybrbr' A thrilling, twisting trip through the darkest corridors of the human mind' Daniel H. Wilson, New York Times bestselling author of Robopocalypsebrbr'A tour de force: a clever and visceral thriller' Lincoln Child, New York Times bestselling authorbrbr'Dark, stylish and packed with jaw-dropping twists . . . an astonishing piece of work' M. W. Craven, author of The Puppet Showbrbr'A superior thriller, at once stylish, absorbing and compulsive' Laura Carlin, author of The Wicked Cometh brbr'Well-crafted gothic crime . . . smart, atmospheric' Kirkus Reviewsbrbr'A Gothic masterpiece in psychological horror and creeping dread ' Neil Broadfoot, author of No Man's Landbrbr'Deliciously authentic and darkly atmospheric' Graham Smith, author of Death in the Lakes