Black Diamond, By Martin Walker

During the early pages of Black Diamond, readers unfamiliar with Martin Walker's French policeman, Bruno Courreges, would be forgiven for thinking that they had stumbled into a Tricolore textbook peopled with individuals imagined by Peter Mayle. Regarde: here is the genial police inspector from Perigord who loves to cook hearty dishes laced with the truffles he's found in the woods. Maintenant, here is the mad English woman whom he is dating. Zut alors! A newcomer in town has opened an eco-restaurant. See how he has shut down the local sawmill.

But while Walker's characters seem at first to be familiar types, and his evocation of rural France comforting, with its markets, hunting and meaty meals, things get complicated quickly. For beneath the Gallic charm that Walker conjures so effortlessly are modern mores and characters more convincing – and cruel – than you might at first assume.

As the only policeman in St Denis, Courreges is responsible for everything from crowd control to charity collections. So investigating rumours about a truffle scam in the local market while trying to find out who has attacked a Vietnamese family's stall is more or less business as usual. Dedicated as he is to his job, Courreges is also preoccupied with the local mayoral elections, training the town's rugby team and hunting with his friends.

This mix of petty crime and community life is beguiling, so it's all the more shocking when one of Courreges's buddies is found brutally – and I don't use that word lightly – murdered, having been tortured and strung up seemingly as a warning to others. In discovering why his friend has been killed in such a cruel way, Courreges has to piece together unsavoury facts from France's colonial past, and call on his contacts in the Secret Service. As he realises that there was more to his friend than he ever thought possible, so it dawns on the reader that, while Courreges is devoted to the town he polices and the rural life he enjoys, he is no bumbling plod but a keen investigator.

This sleight of hand continues throughout Black Diamond. There is more to everyone and everything than at first seems, which is true for the book itself. This isn't a bucolic police yarn, despite appearances, but a well-crafted crime novel that cautions against blind belief in people and their motives. Unsurprisingly, given his journalistic career as European editor of The Guardian as well as an author of non-fiction history, Walker writes informatively on France's historical involvement in Vietnam and on the tense contemporary situation between the Chinese and Vietnamese communities from Paris to Perigord.

Perhaps more surprising is the truly winning character he has created in Courreges, who lacks the irritating quirks of some detective heroes and manages to be brave, bright and very human, without the drink problem or delinquent daughter that seem to be de rigueur for his peers on the page. So likeable is Courreges, and so convincing his milieu, that I was desperate for more Bruno as soon as Black Diamond's brisk and brutal conclusion came. Forget a rustic ride through rural France with a few swarthy stereotypes thrown in; as they say in the pages of Tricolore: c'est formidable.