Just finished the seventh in the MATT HELM series and all I can say is "wow..possibly the best in the series so far!"
Published in 1964, THE SHADOWERS is an odd duck for the action/spy/thriller genre, because there isn't a whole lot of any of that. It's a love story, or more accurately,a lack of love story. Helm's character is more defined now, and he is someone unlikeable. His whole motivation for doing this work seems to be he just doesn't like anything---new cars, fancy guns, women wearing pants. he's a worse curmudgeon than me, and he's supposedly only around 40 (although that time line is starting to unravel).
I can't reveal too much of this book, since it would take away some of the enjoyment for a potential reader. 50 years on, this is still a "page turner", and I use that phrase believing it is used way too often. The twists keep right on turning, right until the last sentence.
You'll find yourself thinking "why do I care what happens to this jerk?" and then you realise this isn't a "hero overcomes adversity" tale like so many modern action tales. It is a given that Matt will survive, at least for 30 or so novels.There is little suspense. There is not much of the gadgetry found in this series either--the only guns used in this one are a cheap .22 and a .38 revolver. Matt eschews fancy cars. He drives someone else's Renault in this one (although he admires another character's Austin Healey). Also missing are romantic exotic locales--The Shadowers takes place in Pensacola, Florida mostly. What we do have is a great tale of asocial operative and SOB Matt Helm taking stock at all the collateral damage that happens around him.
It's a shame a serious cinematic version never materialized. But then, this stuff is not for everyone. But a lot of my reading friends would like it.