Ros Taylor has been raped and her friend Jo murdered by an intruder who broke into their flat one summer night. Because she'd been drugged by her attacker, Ros can remember almost nothing of what took place. During the investigation, Ros begins a relationship with one of the detectives, Bill Thompson, who discovers, by chance, that she has the rare ability to lie convincingly. He is certain that he knows who the murderer is, but doesn't have enough admissable evidence to secure a conviction, so he persuades Ros to lie in court, identifying his suspect as the man who attacked her. But after the suspect has been convicted, Ros becomes the victim of a stalker - a stalker who says that he, and not the man now in prison, is the real killer. Knowing that Ros can't confess to her own perjury, he begins to play with her as a cat with a mouse. Soon she fears for her own life. Bill is torn between protecting her and telling his superiors about his own part in the deception. How much simpler it would be, he reasons, just to take the law into his own hands and step up from perjury to murder. But first he needs to establish exactly what the truth is, and whether the lie that Ros told so convincingly in court was the only one she told...
