Charlie Barber, portrayed by Adam Driver, is a prominent theater director in the vibrant world of New York City. His theater company is currently staging a production featuring his wife, Nicole Barber, played by Scarlett Johansson, who once enjoyed a career as a teen film actress. As the couple navigates their turbulent marriage, they engage with a mediator who suggests they express what they appreciate about each other in writing. However, Nicole hesitates and ultimately they abandon counseling.
When an exciting opportunity arises for Nicole to star in a television pilot in Los Angeles, she decides to make a temporary move, taking their young son, Henry, played by Azhy Robertson, along to stay with her mother, Julie Hagerty. Meanwhile, Charlie opts to remain in New York, focused on transitioning the play to Broadway. Though they initially agree to a friendly separation without legal representation, Nicole ultimately hires family lawyer Laura Dern under the guidance of her new producer. She confides in Nora about the deep-seated issues in her marriage, detailing how she felt increasingly overlooked and expressing her suspicions of Charlie's infidelity with a stage manager.
During a family visit to Los Angeles, things escalate when Nicole serves Charlie with divorce papers through her sister, Merritt Wever. Faced with the reality of his situation, Charlie consults Ray Liotta, a formidable lawyer who encourages him to take a more aggressive approach, but Charlie chooses to leave without legal representation. Soon after, Laura Dern urges him to secure a lawyer quickly to protect his rights as a father. He eventually enlists the help of Alan Alda, a kind-hearted attorney who promotes a peaceful resolution.
Despite Charlie’s assertions that Nicole desires an amicable divorce, Nicole frequently adopts a more hostile stance, seemingly following Nora's aggressive strategies. Bert advises Charlie to maximize his time with Henry, while Nicole attempts to minimize their interactions. A confrontation sees Nicole accusing Charlie of cheating, revealing the painful dynamics of their faltering relationship.
Following Bert’s guidance, Charlie rents an apartment in Los Angeles to bolster his custody chances. Yet, he resists advice to abandon his New York residency, leading to increased tension. As the legal battles escalate, each party's lawyer scrutinizes the other's character, with Nora bringing up Charlie’s past indiscretions and Jay maligning Nicole’s reputation.
During a shared moment away from the lawyers, a seemingly amicable discussion descends into a fierce argument. Nicole accuses Charlie of blatant selfishness, leading to a moment of emotional upheaval when Charlie, overcome with frustration, damages the apartment and then breaks down in remorse. They find solace in each other as they work towards a more equitable divorce agreement.
Fast forward a year: Charlie's play has flourished on Broadway while Nicole has moved on, embracing a new relationship and earning an Emmy nomination. Charlie informs Nicole of his upcoming move to Los Angeles for a year-long residency at UCLA to be closer to Henry. In an emotional moment, Henry urges Charlie to share aloud the list of things Nicole appreciates about him, which she wrote during their counseling sessions. As Charlie reads the heartfelt notes, Nicole watches from a distance, moved by the moment.
At a Halloween gathering, Nicole’s kindness shines through as she offers to let Charlie take Henry home, despite having custody that night. As Charlie exits, cherishing a sleeping Henry, Nicole stops him to tie his shoe, a brief yet poignant gesture that signifies their evolving relationship. They part ways with gratitude, embracing the complexities of their intertwining lives.