Speed. In 1947, it represented the difference between victory and annihilation. After Hiroshima, the ability to deliver a nuclear device to its target faster than one’s enemy became the singular obsession of American war planners. And so, in the earliest days of the Cold War, a highly classified program was conducted on a desolate air base in California’s Mojave Desert. Its aim: to push the envelope of flight to new frontiers. There gathered an extraordinary band of pilots—including Second World War aces Chuck Yeager and George Welch—who risked their lives flying experimental aircraft to reach Mach 1, the so-called sound barrier, which pilots called “the demon.”

Officially Yeager was the first to achieve supersonic flight in the Bell X-1 “Glamorous Glennis,” but drawing on new interviews with survivors of the program, including Yeager’s former commander, as well as declassified files, Hampton presents evidence that George Welch, a daring fighter pilot who shot down a remarkable sixteen enemy aircraft during the Pacific War, likely met the demon first, though he was not favored to wear the laurels, as he was now a civilian test pilot and not part of the government’s X-1 program.