The Book of the Week is Scratch One by Michael Crichton (1942-2008), under the pseudonym John Lange. This is a very hard to find first printing, paperback original, published in 1967.
Scratch One was the second of eight novels Crichton published as by John Lange. The Lange books were sexy thrillers, commonly featuring half-naked women on the covers. Scratch One follows a lawyer who is mistaken for a secret agent while traveling through Europe, and before long he has to start acting like one.
While Michael Crichton's early work under pseudonyms was well-received in the mystery community -- A Case of Need as by Jeffery Hudson even won an Edgar Award for best mystery novel of the year -- Crichton's great commercial success came only when he switched to science fiction. This is perhaps surprising, as his anti-technological bent is atypical of the SF genre, but Crichton found a lucrative niche writing science fiction that appealed to non-SF readers.