When Philip Nelson is killed in a farm accident, the pathologists conclude they have a straightforward case of man vs. machine and the machine won. Sam makes an error however and soon finds evidence that points to murder. The police suspect his handyman, all the more so when they discover he was having an affair with Nelson's wife. When the murders continue however, Sam uncovers evidence that connect at least some of the men to events in Northern Ireland when they served in the army together many years before. Sam is more than a little surprised when Charlie, an old friend, sounds her out about taking up a new Chair in Forensic Pathology at London University. DI Michael Connor and his wife take a stab at a reconciliation but he finds it difficult to forgive her infidelity and realizes he has feelings for Sam.

Sam looks for connections between Ian Neal and a killing in Northern Ireland in 1985.