Professor Sue Black investigates a Christmas murder mystery to show how serious crimes are solved when there isn't a body. Sue is joined by an expert team including leading police specialists, forensic scientists and an award-winning dog. Assisting them, the audience help to unravel the mystery, using the latest forensic cameras, fingerprint techniques and DNA analysis. Remarkable soil analysis shows how a suspicious pair of muddy boots can be traced back to the most precise location. With insights into real serious crime investigations, Sue and her team draw on all their experience to solve the mysterious case.