Definitely bad, but…better? At least marginally moreso than the previous two books in this limited series from the 1960s, both of which were written by "Max Walker" (sometime pen name of Michael Avallone, who also wrote a number of similar junk tie-ins for "Hawaii Five-O," "The Girl/Man From U.N.C.L.E." and "Mannix"), and which were just awful. But for this one, the good folks at Popular Library returned to "John Tiger" (aka Walter Wager), who also wrote the slightly better first "M:I" novel, and so this final (thank God) book actually reads more like an episode of the TV show — which in itself isn't really anything to be proud of. (Wager also wrote all the equally awful "I Spy" novels around the same time.)
Of personal interest, just as the previous (i.e., third) "M:I" book had Barney training on a LINK simulator (a company I worked for in the mid-'70s), this book takes place largely on the sidelines of an international machine tool trade show, a number of which I frequented for a different job in the '80s-'90s. So fond memories — but again, just terrible books. Really, about the nicest thing I can say for ALL these books here is that I'm impressed that after more than half a century, the pages still aren't falling out of these things — so kudos to the books' binder, if no one else involved in this sorry project.
Fans of the TV show probably remember the original cast — or at least the Season Two "original cast," when Peter Graves replaced Steven Hill. However, even I had forgotten what a fluid line-up the show had from then on; the husband-and-wife team of Barbara Bain and Martin Landau both left after Season Three, to be replaced by Lesley Ann Warren and a post-Star Trek Leonard Nimoy, and then Sam Elliott replaced Peter Lupus a year later. So, y'know, that.