Forty nine years ago astronauts Virgil "Gus" Grissom, Ed White and Roger Chaffee strapped into their Apollo Command Module (CM) to perform a "plugs out" test, designed to simulate the CM operating on internal power. They were to be the first crew to fly Apollo and begin the final phase in America's mission to land a man on the moon. Gus Grissom would be the first astronaut to fly in all three programs, Mercury, Gemini and now Apollo. Ed White was the first American to walk in space and Roger Chaffee was to make his first trip into space.

The spacecraft was undergoing a long series of tests designed to verify its readiness for flight. Throughout the process, the spacecraft's performance is reviewed and design changes recommended as a result. Astronauts and engineers work together to ensure the spacecraft is ready and as safe as possible. Safety concerns, such as those around the amount of highly flammable material, such as nylon straps, in the CM, are reviewed and fixes implemented if they are deemed necessary. In the case of the flammables, they ultimately weren't replaced.

After the astronauts entered the CM and were strapped in the hatches were closed and the CM pressurized using a pure oxygen environment. The testing dragged on through the evening due to a number of technical glitches. The at 6:30 PM, things started going wrong. A spark ignited a fire fueled by the O2 environment and "Fire" is heard over the communications system. Fifteen seconds later, pressure build up in the CM results in its rupturing. Rescue crews were hampered by the resulting intense heat and smoke. The fire was eventually put out and the rescue operation becomes a retrieval operation as the bodies of the astronauts are removed from the CM. 

Gus Grissom, Ed White and Roger Chaffee become the first US astronauts to die in a spacecraft. Apollo is put on hold until the fire's cases can be determined and the spacecraft redesigned to make it safer. Ultimately, five probable causes are identified:

• An ignition source, probably exposed electrical wiring
• The high pressure pure oxygen atmosphere
• Flammable materials in the CM
• A hatch cover design which made it hard to open quickly at the cabin's pressure
• Inadequate emergency preparedness

The remaining CMs were used for unmanned test flights. The redesigned CM, known as the Block II, flew 22 months later as Apollo 7. Two and a half years after Apollo 1, Neal Armstrong walked on Ohio's Moon.