A sheep's head is impaled on a farm gatepost, underneath is a note which reads 'You next'. It is the first of a series of bizarre and horrific events investigated by scientists from the Chepstow forensic science laboratory and police from the Avon and Somerset constabulary.

On 22 Oct 1981 an American disappeared in Paris. His Israeli wife disappeared in England ten days later. Police enquiries led to a strange and squalid bungalow on the south coast, the home of the couple's son.... The case was investigated by the Hampshire police and scientists from the Home Office Forensic Science Laboratory at Aldermaston. The names of people and places have been changed.

A father and son lie dead outside their front door - the Victims of an IRA shooting. 400 yards away lies a half-eaten apple ... The names of people and traces have been changed.

A bank teller is shot dead by an armed robber. Eye-witness accounts conflict and are virtually useless. The police do not know where to start looking. However, the shattered bank screen and the shotgun pellets and cartridge wadding recovered from the victim provide some vital clues ...

Douglas Scott 's life is falling apart. He faces the sack and has problems at home. A week after his 50th birthday his wife is found dead in a caravan, apparently the victim of toxic fumes from a gas lamp...

An 11-year-old boy is the victim of a sexually-motivated killing. Police enquiries in the homosexual community lead nowhere. However, some tiny fibres found on the body attract the attention of the forensic scientists...