DCI Burnside arrives to investigate a murder which looks like part of a series of male rapes gone too far. Andy Wilson, one of the previous victims remembers something about an angel when he was attacked. Following a statement from taxi driver Steve Sanderson, DC Holmes finds a man matching Sanderson's description on CCTV tapes: his name is Mark Angelis and he works for a courier service with an angel logo. Although DS Boulton arrests Angelis in possession of a knife, he insists it is for self defence against the rapist. DS Stanton visits a profiler at Scotland Yard, and later discovers that taxi driver Sanderson has made a similar statement to Stafford Row station. Stanton and Proctor visit Sanderson's wife, and discover evidence that he is the culprit. They call Burnside to tell him, but he's in the back of a cab - Sanderson's cab...