The Chameleon's Shadow, by Minette Walters

A demobbed psychopath meets his match in a dumb-bell twirling lesbian GP

Minette Walters has never been afraid of tackling contemporary problems in her crime fiction, and this book takes her to the heart of an issue for our times. Lieutenant Charles Acland has returned from Iraq with horrific injuries. Thanks to modern surgery, he survives, though badly disfigured. But are his outward scars reflected in psychological changes that have made him a dangerous psychopath?

Acland displays aggression towards women and attacks his frail fiancée Jen, a slender Uma Thurman lookalike. Discharged from hospital, he seems right in the firing-line as a potential criminal, even though he claims respect as a wounded hero. When three men, possibly gay, are murdered in an area where he has violently attacked a fellow-drinker, his paranoid rages make him a compelling suspect.

Where a lesser crime writer might suffer failures of empathy, Walters' imagination is especially good on the fantasies of hatred and revenge engendered by war. Her unwillingness to use the easy explanations of criminality so common in crime fiction, and her determination to delve deep into Jungian questions, give the book the layers of depth that we expect of the "literary" novel.

Acland's injuries alone may not have brought about a change. Jen testifies that before his last tour of duty, he showed violence towards her. He is now a disfigured misfit in the middle-class society to which he formerly belonged. We dive with him into the underworld of drifting ex-soldiers, abandoned by society, mostly victims of drink and drugs.

When Acland is found by an unlikely guardian angel, she too turns out to be a misfit. Jackson is a massive, weightlifting lesbian GP stubbornly working with down-and-outs. She discovers evidence that the cool blond fiancée is not all she claims to be – but does it take the burden of guilt away from Acland? The investigation raises many questions about the nature of criminality, including the interesting possibility that some people may not be vicious in themselves, but the human catalysts who can trigger psychotic attacks in others.

The thriller element of the book is a strong narrative of investigation divided between forensic and medical viewpoints, but it hangs on the creation of two compelling people: the bewildered and angry army officer, and the determined, quick-minded Dr Jackson. The reader often wants to meet Walters' people again, and the dumbbell-twirling doc is one such memorable character.

Macmillan, £17.99. Order for £16.29 (free p&p) on 0870 079 8897