Ros Tyler wakes from a drugged sleep to find that her flatmate is dead and she herself has been viciously sexually assaulted. She has also suffered acute memory loss and has no recollection of events of the previous night. The DI leading the investigation finds himself falling for Ros and becomes convinced of the killer's identity, but his world is turned upside down when the CPS decide not to prosecute. After deciding to lie, Ros tells the court that she can identify her attacker. He protests his innocence but the decision goes against him. Soon she starts to receive anonymous letters from someone who knows that she has lied. Her relationship with Will changes and the pressures begin to show. She soon discovers that the truth can be more dangerous than a lie.