In 2006, a series of explosive fires ravaged pig farms across the U.S. and Canada, leaving a wake of destruction and death. No one could figure out the cause, but there was a pattern: all of the barns were new and all of them were enormous. There was also a recurring clue: a peculiar and mysterious foam rising from the barns' manure pits prior to the fires. So, was the goo responsible for this outbreak of infernos? Fire investigators, scientists, and a waste management specialist join forces to get to the bottom of this perplexing puzzle. Air Date: Jul 24, 2013