Britain’s Special Air Service—or SAS—was the brainchild of David Stirling, a young aristocrat whose aimlessness belied a remarkable strategic mind. Where most of his colleagues looked at a World War II battlefield map and saw a protracted struggle, Stirling saw an opportunity: given a small number of elite men, he could parachute behind Nazi lines and sabotage their airplanes and supplies. Defying his superiors’ conventional wisdom, Stirling assembled a revolutionary fighting force that would upend not just the balance of the war, but the nature of combat itself. Bringing his keen eye for detail to a riveting wartime narrative, Ben Macintyre uses his unprecedented access to the SAS archives to shine a light on a legendary unit long shrouded in secrecy.