When a powerful tornado tears through Nashville and endangers a country music festival, Captain Don Hart leads fire station 113 on a harrowing rescue mission. Meanwhile, the Hart family contends with the fallout when a long-held secret is revealed.

A tornado's path leads the Station 113 team to an intense rescue at a water tower. Ryan and his wife reach a turning point, while Dixie has an assignment for Blue. Cammie coaches a distressed teenager through her mother's childbirth.

Amidst multiple crises, Ryan steps up to lead Station 113. The team responds to a dangerous call of a child trapped in a trailer hanging off a historic Nashville bridge. Meanwhile, Blythe pays a long-overdue visit to Dixie.

Don and the 113 team respond to emergencies at a waterpark and a sorority house. Meanwhile, the crew puts Blue's skills and knowledge to the test as he trains for his firefighter exam, while Blythe digs into Blue's past.

With mounting pressure from his peers and family, Blue takes his firefighter exam. Meanwhile, Roxie and Taylor search for the identity of an unconscious girl and respond to a high-stakes emergency involving two abducted children.

As Don, Blue and Ryan take extreme measures to prevent a distillery explosion, the 9-1-1 call center is disrupted by budget cuts and hackers. Amidst the chaos, Blythe faces an emergency of her own.

Nashville is under siege, with each missed ransom escalating the stakes. As the city descends into chaos, Don grows desperate after losing contact with Blythe and races to find her before it's too late.

Time is running out as ransom demands and medical emergencies escalate in Nashville, then a power outage triggered by the hackers wreaks havoc at the hospital.

Dixie's worsening polyps push her to take matters into her own hands. Don and Blythe's marriage is put to the test, while Ryan and Samantha reconnect.

Roxie notices Don is having panic attacks, and he finally comes clean about his past resurfacing. Meanwhile, Cammie begins to face reality when she starts attending a grief counseling group.

Flashbacks reveal how a devastating house fire reshaped Don's life, along with how he later met Dixie and Blythe. Meanwhile, the 113 responds to a cyclist pinned against a tree after being hit by a car.