Anna Wyncomb is a barista in a coffee shop, grappling with the aftermath of her mother Mary's passing nine months prior. Her father, Ed, has been dating Chuck in the meantime, which adds to her complicated feelings. One fateful evening, Anna and her best friend Charleen, a spirited police officer, inadvertently set the coffee shop ablaze after indulging in a joint. Haunted by guilt and now financially strained, Charleen introduces Anna to an underground all-female fight club, where she meets Bear, the club's manager and referee.
Charleen explains that victorious fighters have the opportunity to display their names on dollar bills affixed to the wall, transforming the fight club into a sanctuary for women seeking to tackle their life's challenges. Encouraged by her friend, Anna hesitantly agrees to step into the ring, only to find herself swiftly knocked out in her first fight. In a twist of fate, Anna learns that her mother was the founder of this very fight club, a secret she had kept from Anna for years, passing away from cancer six months after her last match.
To further her journey, Anna encounters Jack Murphy, a former boxing coach turned restaurant worker, who agrees to train her. During her training, she comes across Olivia, an undefeated fighter who becomes an immediate rival. Sensing the challenge, Anna boldly accepts a fight against Olivia, and as weeks go by, she builds confidence and begins to win her matches. However, a complicated romantic tension arises between Anna and Dr. Roy Park, the attending physician at the fight club, who has a history with Olivia.
After a series of intense encounters where Olivia dominates her opponents, Anna decides she's had enough, realizing that fighting might not be the answer to her problems. Yet, Jack's impassioned words inspire her to face her fears head-on. Unexpectedly, a heart-wrenching call from Chuck reveals that Anna's father has suffered a heart attack. Upon visiting him in the hospital, Ed confides that he knows about the fight club’s ownership, which was passed down to Anna by her late mother. Encouraged by Charleen to sell the fight club and start anew, Anna struggles with her decision but ultimately reconnects with Roy, who admits he has only ever been interested in her.
On the night of her pivotal showdown with Olivia, Anna feels both fear and determination, driven by Jack's coaching to confront her anxieties. What follows is a fierce battle in which Olivia initially has the upper hand, but Anna unleashes her newfound strength and employes a strategic headbutt to secure a surprise victory, marking Olivia's first ever loss. As chaos descends upon the venue with police arriving to raid the fight club, Olivia pays her respect and, alongside the other fighters, makes a hasty exit. Contrary to Charleen's pleas to leave, Anna stands her ground, claiming her rightful ownership of the club, resulting in her arrest.
Once bailed out by Charleen, Anna faces trial for her actions, with Chuck defending her in front of Judge Naomi Andrews, an old friend of her mother's. Ultimately, Anna is acquitted of all charges. In a triumphant turn of events, three months later Anna has revitalized the fight club and engages in a friendly match against Charleen. To everyone’s surprise, the two end up knocked out simultaneously, prompting Anna to call Roy for medical assistance. Later on, when Anna visits Jack to settle her training fees, she finds herself astonished at the additional costs she must cover.
