A serial killer is on the loose in Richmond, Virginia. Three women have died, brutalised and strangled in their own bedrooms. There is no pattern: the killer appears to strike at random - but always early on Saturday mornings. So when Dr Kay Scarpetta, Chief Medical Examiner, is awakened at 2:33am, 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.