Why Pick On Me?  (Paperback, James Hadley Chase)

Milly Lawes, a Piccadilly streetwalker, found a strange ring in her room one day. An hour later, Milly was dead, and the ring gone. Scotland Yard knew all about the ring, though; so did the secret Service-and so, before very long, did Martin Corridon, ex-commando, ex-M15, ex-ethics of any kind... Corridon didn't really want to know, didn't want to work with the Service again-but Milly had been a sort of friend, and the thought of her cut throat and blood-soaked bed was enough to send him off on a trail of sabotage and murder. A trail that had him running as hunter-and hunted...