In the quaint town of Fair Oaks, Kansas, Betty Sizemore, a diner waitress played by Renée Zellweger, is an avid follower of the soap opera A Reason to Love. Unbeknownst to her, her husband Del, a car salesman, is embroiled in both an extramarital affair and a drug-dealing scheme. On her birthday, when Betty inquires about borrowing a Buick LeSabre, Del, her husband, suggests she take a different car. However, she manages to sneak away with the keys to the Buick, completely ignorant of the hidden stash of drugs in the trunk.
Her life takes a shocking turn when two hitmen, Charlie and Wesley, come knocking at their door. Charlie, who is intent on retrieving the drugs, threatens Del, leading to a tragic misunderstanding that results in Del's scalp being taken and ultimately his death at the hands of the horrified Charlie. Betty witnesses the horrific act, leading her to slip into a fugue state, adopting the identity of a nurse from her beloved soap opera.
While Sheriff Eldon Ballard and local reporter Roy Ostery investigate the crime scene, Betty remains eerily calm as she packs her belongings. She spends the night at a friend's place and, later, drives off in the LeSabre to a bar in Williams, Arizona. There, she spins tales of her non-existent engagement to a renowned surgeon, drawing from the character she embodies. Meanwhile, Charlie and Wesley, aware that Betty saw Del's murder, are on her trail, but Charlie finds himself inexplicably drawn to her.
Making her way to Los Angeles, Betty struggles to secure a nursing position due to her lack of credentials. However, she impresses hospital staff by saving a life using techniques picked up from A Reason to Love. Despite her unorthodox entry into the medical field, Betty becomes a favorite among patients, finding shelter with Rosa, the sister of the young man she saved. Rosa, a legal secretary, helps Betty search for her fictional surgeon fiancé, only for Betty to remain blissfully oblivious to the fact that "David" is merely a character.
Things take an exciting turn when Betty's lawyer offers her tickets to a charity event featuring George McCord, the actor who portrays David. Although initially dismissive, George becomes intrigued by Betty's unwavering belief in her character, ultimately leading him to develop feelings for her. Encouraged by his producer, he decides to cast her as a new character on the show: Nurse Betty. However, when Betty arrives on set, reality crashes down as she realizes she’s been living a fantasy.
The climax approaches when the hitmen confront Betty and Rosa at their home, taking them hostage. Just as tensions rise, Sheriff Ballard arrives on the scene, leading to a standoff where Wesley is shot dead. In a heart-wrenching turn, Charlie, unable to confront his actions, takes his own life. George, shaken yet sincere, apologizes to Betty and extends an offer for her to join the soap opera as a full-time cast member.
In the aftermath, Betty appears in 63 episodes of A Reason to Love, finally taking a long-awaited vacation to Rome, while also setting her sights on a future in nursing. Through this tumultuous journey, she finds both tragedy and hope, proving that life can sometimes imitate art in the most unexpected ways.
