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.

Left wing writer Tom Flannery rings for the emergency services when he finds his investment banker wife Bridget dead at the foot of their stairs, lying in an unnaturally large pool of blood. Both Harry and Detective Superintendant Jenkins find the death suspicious as some blood seems to have been cleaned from the wall, making a 'void', but then Jenkins dislikes Flannery's anti-police strand in his writings and she knows Bridget was insured. Nikki believes the death was an accident until Bridget's sister Muriel tells her that the first Mrs. Flannery also died after falling downstairs.

At the coroner's inquest into Bridget's death Nikki and Harry give conflicting evidence though it turns out that a young policewoman made the 'void' when she slipped on the blood and touched the wall to steady herself. Disturbed mental patient Diamanda Yannis,who had previously attacked Tom's daughter Anna, a nurse, was seen at the Flannery house, covered in blood but she dies after a fight with police. Harry has the first Mrs. Flannery exhumed, proving that someone killed her. Tom admits to Nikki it was him,during a drunken argument over his wish to marry Bridget. He also claims that he killed Bridget but Nikki believes he is shielding somebody else.Is he?