Somewhere high above the Himalayas, the aircraft’s wings iced over. The best guess is that it stalled out and dropped like a rock, landing in the rugged mountain jungle, its location a mystery that would endure for more than 70 years. Browne, who grew up in the Chicago suburb of Winnetka, Capt. John Dean, the pilot and a veteran of the legendary Flying Tigers, and a Chinese crewman were listed as missing in action.

The plane was one of hundreds to go down in the rugged and remote mountain region fliers dubbed “The Hump” by American fliers who dodged Japanese fighter planes, steering their unarmed and rickety aircraft for 20-hour stretches with unreliable instruments in winds that could reach 200 mph. Experts believe more than 700 planes crashed trying to surmount the Hump, making the Himalayan region an inaccessible tomb of legendary fliers and rusted fuselages....