Owen, Tommy and the rest of the 126 are being called into action to a county fair when a ‘derecho,’ a series of fast-moving group of severe thunderstorms, hit Austin, causing hurricane and tornado-force winds, heavy rains, flash floods and a wide path of destruction. And just when they think it couldn’t get worse, an even more rare weather phenomenon, a ‘heat burst,’ causing temperatures to go up to 122 degrees Fahrenheit, hits the city.