An insurance investigator, William Byfield, is found dead, apparently having suffocated from exhaust fumes piped into his car, which suggests suicide. However, on closer examination, Harry suspects he may have died from cyanide poisoning. Byfield's replacement, Clare Ambler, believes his death may be linked to his latest investigation involving the death of Stephen Connelly, and Leo is worried that he has no recollection of the case as he was apparently the pathologist who did his post-mortem. The case becomes more complicated as Harry meets up with grief councillor Rebecca, who he worked with before, who turns out to be Connelly's widow, while Ambler convinces the police to investigate Leo for fraud. With Leo's career at risk, it becomes ever-more crucial to get to the bottom of the case.
