When a teenager's body is located in a shallow grave, a soil specialist is called on to unearth evidence to convict the killer. And as a murder investigation on Merseyside stalls, a fibre expert is enlisted to revive the case.

Detectives hunting the killer of a young woman from Bolton require the help of a fibre and DNA specialist to arrest their suspect. And police seek the help of a body fluids expert after a bizarre rampage in the Cotswolds.