The Devil's Cave By Martin Walker

It is springtime France's Perigord, a time of beauty and calm. But not for Bruno, chief of police of the small town of St Denis. A woman's body has been found on a boat, bearing signs of a black magic ritual. Bruno has too much on his plate as it is - mediating a domestic abuse case that needs careful handling and a dodgy local development proposal that seems just too good to be true. But a murder case must take precedent and the roots of this one lie buried deep in the past - linked to a chateau above a bend in the river, to the reclusive old woman who lives there, and to the secret hidden in the Devil's Cave.