"Once a Spy" is about a retired CIA black ops man, Drummond Clark, who suffers from Alzheimer's and thus is perceived by his ex-colleagues as a risk to leak their secret of "the device," which is vital to national security. So they conclude that it's for "the greater good" that Drummond have an accident. A fatal one, of course.
The only person Drummond can rely on for aid is his estranged son, Charlie, a career underachiever and professional horseplayer who only ever known his father as a dull appliance salesman. Charlie tries to institutionalize Drummond, but before they can get to the nursing home, bullets start flying, and things start blowing up, almost every page.
In vivid, lighting-paced chapters that read like scenes from the best action movies, Charlie must solve the mystery of why assassins are trying to kill him and the old washing machine salesman, then develop the spine to do something about it. Drummond, in periodic episodes of lucidity, remembers bit here and there that offer clues. Sometimes he aids in their defense too--he fights and shoots at a world class level. Other times, he imparts tradecraft, like hot-wiring cars and disguise techniques. The previously estranged father and son come together, poignantly, and making a smashing team. Literally smashing.
The thrilling story that results is not just an adrenaline-fueled rollercoaster ride, as many others have commented. It's a revelation in the thriller genre, as novelist Lincoln Child avows. LeCarré books are wonderfully crafted (Thomson is no slouch with the written word either) but slow-paced. Other luminaries in the genre, Flynn and Thor, don't have characters with the depth and dimension of Drummond or Charlie. Or the wit. Thomson, a national secuirty reporter, also manages to add a layer of verisimilitude and insight of some of the genre's headier members, Ignatius and McCarrie.
I've never read anything like "Once a Spy." Hopefully there will be a sequel. Five stars and highly recommended on top of that.