Shortly before 1 o'clock on the afternoon of January 27, 1967, three men rode a noisy metal elevator to the top of a steel tower at Launch Complex 34-A at Cape Canaveral, Florida. Virgil I. "Gus" Grissom, Edward H. White II, and Roger B. Chaffee would shortly become the first Americans to perish while performing duties directly associated with spaceflight.

The task before these three men and their 1,000 support personnel was known as a plugs-out test. Spacecraft 012 was scheduled to ride a Saturn IB into space on mission AS-204, the first piloted flight, the following month. The plugs-out test was designed to verify that the spacecraft and launch vehicle could operate on internal power only, after all electrical, environmental, and ground checkout cables had been disconnected.

At the time of the AS-204 test Grissom was a veteran space traveler. He had flown the second suborbital flight of...