Two police officers are about to head home when they receive one last call. En route to investigate, the patrol car spins off the road, killing one of the exhausted cops and leaving the other in critical condition. Detective Peter Diamond is assigned to look into the case. His supervisor is desperately hoping Diamond will not discover that the officers were at fault. Instead, Diamond discovers something even worse --- a civilian on a motorized tricycle was involved in the crash and has been lying on the side of the road for hours. Diamond administers CPR, but the man’s fate is unclear. As he lingers on life support, Diamond must wrestle with the fact that he may have saved the life of a serial killer.
In a Sussex town on the south coast of England, a widely disliked art teacher at a posh private girls’ school disappears without explanation. Meanwhile, a Sussex detective has been suspended for failing to link DNA evidence of a relative to a seven-year-old murder case. When detective Peter Diamond realizes that the suspended officer is an old friend who is not known to make such mistakes, he begins to notice unsettling connections between the cold case and the missing art teacher. Could the two mysteries be connected?