An unexpected arctic cold front brings an ice storm to Austin and a variety of weather-related emergencies. Meanwhile, Owen deals with the fallout of the 126 closing, as Tommy, T.K. and Gillian settle into new employment, and Judd and Grace prepare for the birth of their first baby.

Carlos is determined to solve his father's murder. Owen is offered a life-changing opportunity. Judd gives into his demons as Tommy begins her treatment.

Owen and the 126 deal with the aftermath of the asteroid crash in Austin while an even greater threat looms.