I picked this up off the dupe shelf the other day and couldn't remember if I'd read it or not. So I opened it up and started it. After the first couple of paragraphs, I recalled the main plot twist, but I kept on anyway. Aarons was a real pro. There's nothing in this book to make someone claim him as a favorite writer, but it's solid stuff all the way.
I'm always amazed at Aarons' ability to describe a scene as if he'd visited the very spot, and there's plenty of that kind of work in this book. For example, here's Sam Durrell's trip on a cog railway: "There was a long, narrow valley; a rushing, frothy stream; autumnal flowers in the meadow; an area of boulder-strewn fields in deep shadow from the rugged aretes on either hand. The few farms here were linked by a single road that twisted to follow the cog railway line as much as possible. Finally a gorge opened into a cuplike valley to and from which there was only this one entrance and exit, marked in pines and rubbly slopes."
The plot is a familiar one: Sam Durell, the protagonist in all the "Assignment" books, is tossed out of the CIA because he insists on investigating why his long-time sweetheart, Diedre, has married someone else, and a very suspicious someone at that. Durell soon finds himself working against the CIA and everybody else in Europe. But you can bet he's going to keep on until he gets the answers he's looking for.
By this time, Gold Medal had started giving the series pretty bland covers, which seems especially odd since Aarons gives the readers plenty of scenes that would have been great cover material, one of which would have no doubt been used in earlier years: A woman stripped, tied to a post and whipped; a luscious redhead bound, gagged, and tied spread-eagle on a bed; a mad dash through the crowded shower room of a women's barracks.
The book doesn't offer any surprises, but it's a solidly professional job. If that kind of thing interests you, check it out.