Donald Hamilton is the author of the long-running Matt Helm series. Matt Helm was a US 'counter-agent' - essentially an assassin targeting foreign spies. Helm featured in twenty seven books (over thirty three years) - beginning in the 1960's. Throughout the series, he's tough, ambiguously-aged, a little bitter, a lot macho and very, very proud.
Matt Helm could beat up Jack Ryan. And, judging by the author photograph, Donald Hamilton could as well.
The Shadowers is a relatively early Matt Helm thriller (#7, from 1964). The book starts in the best 1960's male-agent tradition - that is, the explosive death of a loved one. (Presumably, this wraps up any emotional loose ends from #6.) Helm is distraught for the length of three pages, then places a phone call to his boss. Vacation is over, he needs someone to kill.
Fortunately, victims are close at hand. An evil Communist overlord has begun a program of installing evil Communist assassins on American soil. These assassins are shadowing American citizens IN ALL BRANCHES OF GOV'MINT. At any time, the evil Communist overlord can say code-word 'pravda' (or whatever), and, bamf, most of the US civil service will die.
Matt Helm is assigned to find one of these shadowers and then beat the location of the Communist overlord out of them. For completely rational reasons, the US Government feels that the best option is to get Helm to marry one of the targets. Hijinks ensue.
If there is a larger theme, it is about trust. Olivia doesn't trust Helm. Helm doesn't trust Olivia. Olivia's ex-boyfriend doesn't trust either of them. Nobody really trusts (or cares much about) him. The few bit characters that show up are all fairly unmemorable, and when the eventual 'Shadower' is revealed, it has all the impact of a lemon slice hitting the table-top.
The author does, however, win the one of the 'Great Moments in Fiction' award for his treatment of Toni Vail, a secondary female character in the book. Helm kidnaps Vail at gunpoint and escorts her out of a crowded restaurant. (Leaving her boyfriend - never mentioned again - in the bathroom.) Toni is scared but overwhelmed by the size of Helm's massive machismo, and accepts that it was all part of the 'great game' and lets him buy her dinner. She offers him sex (who wouldn't?!) and he turns her down, as he is a Chivalrous/Tragic Figure (what with a wife and recently-deadified-girlfriend). Helm then heads back to the hotel to do his job.
Toni's night, however, has just begun. An evil Nazi/Communist Assassin breaks in to her home and rapes her to get some sort of unspecified revenge against Helm. Understandably peeved, Toni later confronts Helm:
"I told you before I wasn't a sheltered virgin. I've had it rough before. Maybe not this rough, but rough. I'm all right."
Helm, of course, does the 'right thing', and leaves $200 on her desk to cover "damages". The whole sequence is an ethical train-wreck, for Helm and Hamilton alike. Fortunately for everyone, Toni gets killed soon enough, so she's soon off the conscience.
The primary woman in the book (not counting the dead ex), Olivia Marrissey is no less horrible. Although an unspecified 'air doctor' of some sort, she's, frankly, pretty dumb. Most of her time is spent in an obsessive plan to get impregnated by a government agent. (No, seriously.) She's briefly more interesting when Helm mistrusts her, but when her dodgy behavior turns out to be related to an ex-boyfriend (and not, say, the USSR), Helm summarily dismisses her as uninteresting. Which, for the record, she is.
Of the handful of Donald Hamilton books that I've read, this is easily the worst. The plot is straight-forward, dull and, somehow, irrelevant. There's not a lot of depth to Matt Helm or his blushing bride's (Olivia Marissey) character, so even the marital hijinks fall depressingly flat. Somehow, the book even turns Cold War paranoia boring - the global tension taking a backseat to the ongoing, overwhelming misogyny. Matt Helm's series is never great, but in The Shadowers, only his flaws are brought to light.