Friday's Book: Unnatural Exposure Patricia Cornwell

"I squatted close and opened my medical bag," says Dr Kay Scarpetta. "With forceps I collected maggots into a jar. The victim had been decapitated ... arms and legs severed. Stumps were dry and dark with age."

This pathologist, Chief Medical Examiner for Richmond, Virginia, is a phenomenal character. She sells books by the mile through a combination of winsome personality and disgusting habits: namely, a penchant for cutting up bodies in appalling conditions and apparently enjoying it. In each of the seven preceding thrillers, Scarpetta races against time to forestall the activities of a serial killer in a hunt which invariably becomes a personal vendetta on both sides.

That is the formula Cornwell repeats here. Scarpetta begins with the torso bearing strange signs of disease and found in a rubbish dump. The serial killer's weapon of choice is not merely the chainsaw first suspected, but a deviant form of smallpox, while the secondary weapon is the computer used to send taunting and terrifying messages to the good doctor.

Cornwell provides classic detective fiction, with a devilishly clever perpetrator hunted by a forensic expert of conspicuous virtue and the additional, irresistible element of horror. There is a scene with a pathologist lancing pustules on a corpse which is almost vomit-inducing. But for all the gory detail Cornwell's novels are oddly comforting. Virtue will out.

Despite Ring, a cop corrupted by his ambition, the other police are generally decent folk. The rescue services are beautifully trained and ruthlessly efficient, while the FBI are a race of saintly gentlemen - a refreshing change. Nor do we get involved with victims: the dead are pitied and put away after their bodies have yielded the clues to the killer, who could never be confused with the person next door. The comfort-and-scare formula creates great excitement, but irritation does creep in. Scarpetta has become such a superwoman, and the elements of her love life intrude with relentless sentimentality. In the course of the novels, she seems to have lost any reliable assistance; she charges from airport to airport and moans about being tired. The theme for the next book could Scarpetta's nervous breakdown. The clues are already in place in this one; and a jolly good read it was, too.

Little Brown, pounds 16.99