Aged seven, Jane Phillips saw her mother murdered by a man who was never apprehended. Twenty-three years later, now a wife and mother with a second child due, she is convinced that oncologist Andrew Rawlins, whom she sees in a hospital, is the killer, and contacts Alison Hall, the officer in the original case, who is now about to retire. Jane has given up taking her anti-depressants and, coupled with the fact that she has made mistaken claims before, her father Pete and husband Rob are sceptical about this new identification. Furthermore, Andrew's blood, after he submits to a test, does not match the murderer's. Andrew's daughter Emma, a lawyer, visits Jane to warn her off but, despite the lack of evidence, Jane is still convinced that Andrew slew her mother.

With Andrew's DNA results exonerating him, Emma wants him to sue the police, but he refuses and also declines to take action against Jane when she attacks him - though she is made the subject of a restraining order. At the same time, Alison is approached by Jo, a nurse who once worked with Andrew, who claims that he once tried to sexually assault her and was well-known for forcing himself on women. Armed with this knowledge, Jane goes to see Andrew's ex-wife Isobel, to whom he was apparently violent. An angry Emma goes to see Isobel herself in the hope that Isobel will provide the resolution for the whole affair.