I know you all read Ed Gorman's blog, but I wanted to mention this post. Don't miss it. I've already mentioned the book, here, and there's a cover scan.
Gormania: "The cover says:
VIOLENCE IS MY BUSINESS
TURN LEFT FOR MURDER
Two Thrillers by Stephen Marlowe
and the double volume is a February 2006 publication of Stark House Press under the rubric Stark House Mystery Classics ($19.95). In the front matter you’re regaled with an ISBN number (1-933586-02-8) and other publishing impedimenta—and finally the key dates, 1958 and 1955."