LONDON. Early morning, June 2019: on the foreshore of the river Thames, a bag of bones is discovered. Human bones.DCI Samuel Owusu is called to the scene and quickly sends the bag for forensic examination.The bones are those of a young woman, killed by a blow to the head many years ago.Also inside the bag is a trail of clues, in particular the seeds of a rare tree which lead DCI Owusu back to a mansion in Chelsea where, nearly thirty years previously, three people lay dead in a kitchen, and a ba...