The call comes in the early hours. Human remains have been discovered in a suitcase, dumped on the muddy banks of the River Thames. Detective Jack MacIntosh races to the scene. The suitcase contains a human torso, two arms and two legs. It's the body of a young girl. But where is her head? Then a skull is found embedded in the silt of the riverbed. But it doesn't belong to the body in the case. As the river offers up more of its gruesome secrets, Jack uncovers a tangled web of shocking secrets stretching back 20 years.