Critique of Criminal Reason, by Michael Gregorio

Kant and cunning in a cold climate

It's 1804, and East Prussia is not a comfortable place to be. The country is on the brink of crisis. There is talk of revolution in the air. Napoleon is marching eastwards, possibly to attack Prussia.

Hanno Stiffeniis has, on the surface, little to complain of: he is a provincial magistrate whose life revolves around the petty disputes of a small town and the company of his wife and children. But his tranquillity is shattered when a police officer arrives with a royal commission: Stiffeniis is appointed Procurator of Konigsberg and charged with the investigation of a series of murders. Konigsberg is in the grip of winter. The city is rife with rumours that the victims have been struck down by the devil's claw.

There are other mysteries: why has such an important task been given to a junior magistrate? Why is information being withheld from him? Why is he expected to collaborate with a flamboyant follower of Swedenborg, a man who conducts seances with the dead? Is there a political dimension? Further enigmas lurk in Stiffeniis's background.

Fortunately, help is at hand. Konigsberg is the home of the man Stiffeniis admires most: Immanuel Kant, the last great philosopher of the Enlightenment. Now almost 80, Kant is frail and no longer commands the respect he once did. But the old man's mind is grappling with a new work, a Critique of Criminal Reason, and he is happy to put the fruits of his research at the disposal of his former student. Stiffeniis needs all the help he can get - especially after he almost becomes one of the murderer's victims.

Quite the best element in Michael Gregorio's novel is its setting: a luridly tinted version of Konigsberg, where everything is freezing, sinister or decaying. It doesn't entirely convince as history but works splendidly as the location for a grimmer-than-Grimm historical fairy tale for grown-ups. There are some eye-popping Grand Guignol set-pieces - a guided tour of Kant's DIY forensic laboratory, for example, or a side-trip to see a lecherous abortionist in her lair.

As a crime novel, the book is less successful. One suspects that the overcomplicated plot confused its author rather more than its readers, most of whom will spot the solution to the central mystery long before the closing pages. As a protagonist, the unfortunate Stiffeniis lurches from a doomed German romantic to a slightly ludicrous figure, bursting with self-importance. Nevertheless, Gregorio gives us an unusual perspective on history and has a gift for melodrama. This novel is the first of a series, and it will be interesting to discover where Stiffeniis goes from here.

Andrew Taylor's latest novel is 'A Stain on the Silence' (Michael Joseph)