Owen Strand, the lone survivor of his Manhattan firehouse on 9/11, takes his progressive philosophies of life and firefighting down to Austin, Texas, where he helps the firefighters of Firehouse 126 start anew.

The crew races to a disaster at a wave pool, and an outbreak of mercury poisoning that is leaving its victims in a a zombie-like state. Meanwhile, Owen must come to terms with his illness and what the side-effects of treatment may do to his vanity. Also, Michelle follows a new lead on her missing sister while TK is unsure how to handle his budding relationship with Carlos.

Judd calls out Owen's preferential treatment of T.K.. Marjan feels ostracized at her new mosque after another rescue video goes viral. Owen helps Michelle uncover new information about her sister's disappearance.

A massive tornado sweeps through Austin, as Owen, Michelle and their teams race to save those in its path.