This second novel in the series is a great step up from the rather routine MODESTY BLAISE (1965), which is not a bad book in and of itself but it can't help but pale in comparison to the subsequent stories that reveal O'Donnell to be a master of both characterization and page-turning suspense.
SABRE-TOOTH has to do with a Mongolian military megalomaniac (Ooh! Alliteration!) who is assembling and training an army of mercenaries with the goal of seizing oil-rich Kuwait (can you say "eerily prescient?"), but he needs two utterly badassed commanders to lead his men. Aware of Modesty Blaise and Willie Garvin as ideal choices for the role, and equally cognisant of their retirement from professional ass-whuppin' and criminal activity, the blackguard kidnaps a child dear to our heroes and uses her as leverage to ensure their cooperation. Thus pressed into service, Modesty and Willie must figure out how to survive leading an army of cutthroats, rescue their young charge, defeat the hand-to-hand skills of "the Twins," stop the invasion of Kuwait, and somehow escape from an absolutely escape-proof training ground.
This one's as serious as a heart attack, and there's even a sequence in which Modesty endures...Well, let's just say that I had to put the book down for a while before I could continue reading what she was going through, an experience that made me respect her mental and physical skills all the more. HIGHLY RECOMMENDED.