A serial killer is on the loose in Richmond, Virginia. Three women have died, brutalised and strangled in their own bedroom. There is no pattern: the killer appears to strike at random - but always early on Saturday mornings. So when Dr Kay Scarpetta, chief medical officer, is awakened at 2.33 am, she knows the news is bad: there is a fourth victim. And she fears now for those that will follow unless she can dig up new forensic evidence to aid the police. But not everyone is pleased to see a woman in this powerful job. Someone may even want to ruin her career and reputation.