The Shrinking Man is another case of being familiar with the work of an author through secondary sources, primarily movies and Twilight Zone episodes that Matheson wrote or inspired, but completely ignorant of his actual written output. I'd seen both versions(but not the new one) of I Am Legend, but I never got around to reading the novel, as much as I love those films. Similarly The Incredible Shrinking Man is one of my favorite movies of all time, and I'm just now reading the great, slim novel it was based on. I must say I was surprised at just how closely the movie sticks to the books template, with a few changes here and there(that I'll cover a little further on).
Scott Carey, in the opening chapter, is caught and sprayed by a mysterious cloud of mist while on the deck of his boat, and that's enough to start a shocking and regular shrinking(precisely 1/7th of an inch a day). At first he's a curiosity, but as the shrinking goes on day by day, month by month, with no end or variation, the horror quickly sinks in. Chapters detailing important events in Scott's life among his wife and daughter are intercut with longer passages detailing what he believes to be his last week alive. He's reached the height of one inch, and at the rate he's shrinking he ticks off the days until his death, or more accurately his disappearance. These chapters are both tense and psychologically challenging, following his daily life as he struggles for survival, lost in his basement and locked in perpetual mortal combat with a Black Widow larger than he is. The movie takes this slightly jumbled chronology and makes it all more linear, while still keeping the majority of the events as described. Right down to the romantic encounter with a Little Person who is just his height.
The science in the book is largely unexplained, although we do find the source of this phenomena towards the end of the book. It's a mistake, I think, although probably at the time it was seen as a necessary one. I would have been perfectly fine with that vague mist in the prologue, but Matheson tries to pinpoint the actual cause of Scott Carey's shrinking, and spends a bit of time explaining the physics of it, and those are by far the weakest sections of the book. Not only does it ruin a bit of the mystery and slow down the pace a bit, but the explanations are exceedingly hokey, particularly 50 years later when CSI and PBS and the Discovery channel have made everyone an armchair scientist. It's a bit curious that Scott's shrinking is precisely 1/7th of an inch a day, and that that never varies. You'd think that the process would accelerate as he shrank and there became less and less of him to disappear. Or that it doesn't actually happen every day, but only while he sleeps, not gradually throughout the day(and not EVERY TIME he sleeps, but every time he sleeps at night). These things wouldn't be worth mentioning if Matheson himself hadn't tried to address other aspects of how this logically could happen. If he'd ignored this problem it would be easier for the reader to simply let it slide and immerse himself in the book.
But as I said, minor quibbles. The book remains a pretty gripping read throughout, and evoked a few moments where I felt my stomach tightening and became tense and uncomfortable(in a good way) while reading. The ending for the book is almost precisely the same as that of the film, so I can't say that was a surprise. Although the film did make the ending, which is optimistic and uplifting in it's own twisted way, slightly more religious in nature. *Spoiler* When Scott goes to sleep on that last night, he finds it a shock to wake up at all, only to find that he's shrunk to a scale immeasurable by normal standards, and his overwhelming pessimism is replaced by a hopefulness, that life can exist on smaller and smaller scales and he'll keep travelling, keep experiencing, and keep living through them all. That famous line from the film, 'to God there is no zero!' is in the book 'in nature there is no zero!'. *End Spoiler* A small alteration, to be sure, but it does have a pretty large tonal difference.