In January 2016, businesswoman Sadie Hartley was brutally stabbed to death in her own home. This film follows Lancashire Police as they investigate the case from the call-out to the murder scene to the trial of the two female suspects.

Tells the story of how detectives solved a vicious murder - from the first call to the crime scene, through to the convictions of the killers. In August 2016, Sarah Williams and Katrina Walsh were found guilty of the murder of Sadie Hartley. Cameras follow lead detective Paul Withers and his team as the case unfolds, as they unravel lies told by Williams and discovered her accomplice, Katrina Walsh, who claims to have no memory of the crime.