Young policeman Neil Douglas rushes to the aid of a woman who has been stabbed on London's Hampstead Heath. Seeing a man standing over the body, he lashes out with his baton, striking the man in the head. There is just one problem: the man didn't attack the woman; he was coming to her aid. Neil has just put an innocent man in a life-threatening coma. And the killer is still on the loose. Supended from duty and tormented by guilt, he is determined to trackdown the escaped killer. All the while he is taunted over the airwaves by a pretty but bitchy American phone-in show presenter. But who was the dead woman? Who is trying to hide every trace of her past? And does her case have anything to do with another murder case five years ago in which the "innocent man" whom Neil struck was the prime suspect? Neil is determined to find the answers to these questions - even if it costs him his life.