Ian Fleming (1908-1956), a reactionary, nationalist, misogynist snob, was, at his best, a superb writer of thrillers. Not all the Bond books are first-rate, but when Fleming's imagination was firing on all cylinders, he was capable of great stuff.
"Doctor No" (1958) shows him at his finest. Its story is one of his more outlandish, and the romance a little more mushy than usual, but in terms of plot, suspense, and non-stop danger, this is as exciting as the Bond books get. If you've seen the movie, you basically know the plot, though there are a few minor differences. If you've never read a Bond novel before, this is as good a place as any to start.
Bond is sent to Jamaica to investigate the disappearance of a Secret Service agent. It is soon apparent that there is much more afoot than he had anticipated, and a third of the way into the novel, Bond is sailing by night to the island of Doctor No, determined to find out the truth. Along the way the loses a friend, charms a babe, and foils the nefarious machinations of the evil doctor. Oh yeah--and he kills a giant squid.