Most honourable Procurator Stiffeniis, You talents have been brought to Our attention by a gentleman of eminence, who believes that you alone are capable of resolving a situation which holds Our beloved Königsberg in a grip of terror. All Our faith and consideration are due to the notable personage who suggested your name, and that same faith and consideration now resides in you. We have no reason to doubt that you will accept this Royal Commission, and act accordingly with all haste. The fate of the city lies in your hands. —King Frederick Wilhelm III It has been years since Immanuel Kant's landmark philosophical work, Critique of Pure Reason, brought him fame throughout Europe and made him Königsberg's best-known citizen. Now, rumors have begun to surface of a new work by this aging but still acute mind. Yet unlike his earlier work, this book will not examine the mind of the average man, but the mind of the serial killer. Hanno Stiffeniis, a young magistrate, has been called to Königsberg to assist in the investigation of an enigmatic string of murders. Is it part of a plot formed by Napoleon's spies to undermine the Prussian king or the work of a solitary, unknown killer? The case would seem unsolvable, were it not for the assistance and unmatched intellect of his mentor, Immanuel Kant. Together Stiffeniis and the elderly, eccentric philosopher must track down the killer who has the city of Königsberg by the throat. Hugely atmospheric, entertaining, and intelligent, Critique of Criminal Reason marks the outstanding debut of a new name in historical fiction.