there was this skin just hanging down like when a snake sheds its skin. >> firefighters battled the blaze for an hour. when it is finally out, 31 people are dead, and more than 70 others are injured. among the dead is firefighter colin townsley. >> collin, he'd obviously tried desperately to get out of that inferno and cost him his life. >> the king's cross station is shut down. the london underground is crippled. thousands of commuters are stranded. through the smoky haze of the ruins, a mystery emerges. why did a fire the size of a cardboard box explode into a deadly inferno in a matter of seconds? [ female announcer ] new fiber one protein cereal. ♪ yeah, yeah, yeah, yeah! ♪ we are one, under the sun