Cassie is a twenty-six-year-old, highly skilled firefighter and paramedic originally working in Austin, Texas. Her ability to remain entirely calm in emergencies serves her well on the job, but she struggles with emotional vulnerability in her personal life. She relocates to station two in Lillian, Massachusetts. There, she faces a traditional, male-dominated environment where her coworkers dismiss her abilities based on her gender.

Owen is a new recruit at the Lillian fire department. He arrives on the same day as Cassie. He comes from a traditional family of Boston firefighters and perfectly fits the physical expectations of the job, quickly earning the acceptance of the crew. Despite this natural fit, he secretly harbors anxiety about firefighting and dreams of cooking professionally. He forms an immediate emotional connection with Cassie.

Dianadiana is Cassie’s mother, currently living in Rockport, Massachusetts. She left her family when Cassie turned sixteen and has lived independently since that day. She faces new health challenges that cause vision loss and asks her daughter to move in with her. She hopes to use this time to teach Cassie about forgiveness and repair their fractured relationship.

Captain Murphy commands the c-shift at station two in the Lillian fire department. He prefers the traditional ways of running his firehouse and shows immediate skepticism upon learning his new firefighter is a woman. He resists structural changes at his station and remains fiercely loyal to his veteran crew members.

Captain Harris is a veteran firefighter and leader at the Austin fire department. As a trailblazing Black woman in a traditionally male profession, she possesses deep knowledge of workplace prejudice. She attempts to protect Cassie's career after a public incident and offers practical survival advice for her transfer to a new station.

DeStasio is a veteran firefighter at station two in Lillian. He carries deep emotional pain following a tragic car accident that killed his son and ended his marriage. He is openly bitter and hostile toward Cassie. He refuses to accept her presence at the firehouse and actively resists her efforts to improve the station.

Heath is an Austin city councilman. Cassie recognizes him from her high school years, as he caused significant trauma in her past. He unexpectedly appears to present her with a valor award. His presence provokes a violent reaction that upends her career.

Ted is Cassie’s father. He raised her after his wife left the family. He bonded with Cassie primarily through coaching her in basketball during her teenage years. He has successfully moved on and remarried, and he encourages his daughter to help her mother despite their difficult history.

Josie lives next door to Dianadiana in Rockport, Massachusetts. She is a friendly, supportive neighbor who spends frequent time with Dianadiana at their two-person crochet club. She tries to include Cassie in their activities and helps her prepare for social events.

Hernandez is Cassie’s former professional partner at the Austin fire department. He is known among the crew as a ladies' man who frequently participates in workplace pranks. He also demonstrates genuine concern for Cassie's isolated, rigidly ordered lifestyle.

Six-Pack is a firefighter on the c-shift at station two in Lillian. He participates heavily in the crew's hazing rituals. He initially doubts Cassie's physical capabilities and bets against her during fitness challenges.

Case is another member of the Lillian firehouse crew. Like his peers, he operates under strict, traditional expectations of what a firefighter should look like and initially dismisses Cassie upon her arrival.

Tiny is a firefighter at station two whose nickname is deeply ironic, as he stands a full foot taller than Cassie. He represents the physical size advantage the crew relies upon and participates in a free-throw competition against Cassie.

Colleen is Owen's mother. She hosts a large family anniversary party where she eagerly assumes Cassie is her son's new girlfriend.

Big Robby is Owen's father and a veteran Boston firefighter. He recently suffered a heart attack, prompting a major family celebration where he meets Cassie.

Shannon is one of Owen's four sisters. She attends her parents' anniversary party and catches Owen and Cassie hiding in a coat closet.

Amy is Owen's ex-girlfriend. She was beloved by his family and remains a lingering presence in his life after their recent breakup.