It started as a perfectly ordinary flight....United Air Lines Flight 629, carrying 39 passengers and a crew of five, lifted off the runway at 6:52 P.M.
Eleven minutes later the plane was 5,700 feet up and several miles away. Merrill Yanney, who was on duty in the control tower at Stapleton airport happened to look toward the plane. Suddenly he was horrified to see a great flash of light around it. Before his eyes the plane seemed to explode. Large pieces of it fell to the ground in streaks of flame. Rescue teams rushed to the area....But there was no one to rescue. Everybody on the plane had been killed in the crash......

Was this tragedy an accident - or wasn't it? The F.B.I. intended to find out, and they did - in one of the toughest cases they had ever encountered.
The interrupted flight of 629 and three other equally thrilling adventures combine drama, swift action, and the magic name of the F.B.I. to make irresistible Pacesetter reading.