Kate Stone is a career-focused, abrasive Senior Vice President at a New Jersey hedge fund. Her egotistical attitude isolates her from her colleagues; she mocks a pregnant coworker and is generally disliked by her staff. Kate lives a solitary life, often drinking alone.
Her estranged brother, Joe Stone, calls asking her to babysit his tween daughter, Maddie, for one night so he and his wife, Cheryl Stone, can move Cheryl's mother into hospice. Kate initially refuses but reluctantly agrees when she realizes she is their last option. The overnight stay extends into a week as the hospice situation becomes complicated, throwing Kate’s regimented life into chaos.
Kate discovers that Maddie is bullied, socially isolated, and angry. Although her parents try to force her into traditional feminine activities like ballet to help her make friends, Maddie secretly sneaks into the karate dojo next door. Kate begins to bond with Maddie, allowing her to buy a pantsuit for the school dance instead of the dress her parents want, and permitting her to eat chicken parmesan every night. At a convenience store, Maddie befriends a “Juggalo” named Dennis (who calls himself “Baby Joker”).
Later, Kate finds Dennis in her home. Though initially put off by his face paint, she allows him to stay when he explains that Juggalos are a supportive community of misfits who treat each other like family. Kate attempts to give Maddie beauty tips, but Maddie prefers showing off her karate gear. When Maddie fights back against her bullies at school, Pete is called in. Pete is impressed by Maddie’s skill, but Kate is distracted by work.
Erin, a younger analyst Kate is training, begins to threaten Kate's position by ingratiating herself with potential clients. Erin organizes a critical client meeting for Friday night, forcing Kate to break her promise to chaperone Maddie at the school dance. Maddie is denied entry to the dance because she is not wearing a dress. When Kate finally arrives, she finds Maddie ill from a severe reaction to tomatoes, a dietary restriction Kate had ignored. Joe and Cheryl arrive at the hospital, furious with Kate's negligence.
Kate returns to work but finds herself miserable. She visits the dojo to find Maddie, but Pete has not seen her. Joe and Cheryl arrive at the ballet studio to pick Maddie up, only to discover she has been skipping ballet for karate. Realizing where Maddie has gone, Kate tracks her to the Gathering of the Juggalos.
Kate applies face paint to blend in and navigates the crowd to find Maddie. They reconcile, and Maddie is accepted by the group. In the aftermath, Kate loosens up at work, finally making friends with her colleagues and repairing her relationship with her family.
