"The Pembrokeshire Murders" is a true crime documentary that focuses on the investigation of a series of unsolved murders in Pembrokeshire, Wales. The film highlights the efforts of Detective Superintendent Steve Wilkins and his team as they use modern forensic techniques to revisit cold cases from the 1980s and 1990s. The documentary centers on the murders of Helen and Peter Dixon and Graham and Peter's connection to John Cooper, a serial killer. It showcases how advancements in DNA analysis helped to finally bring justice to the victims and their families after decades of uncertainty.