Bill Willis, a celebrated American novelist and World War II veteran, along with his adventurous wife, Marcella, make their home in the heart of Paris during the vibrant 1960s, surrounded by their beloved family. Their tight-knit circle is completed by their six-year-old daughter, Channe, who is as sweet as she is spirited. As much as Marcella yearns for another child, her heartache from multiple miscarriages leaves her family feeling unfinished. However, a twist of fate introduces Benoit, a bashful six-year-old French boy who has been passed through various orphanages and foster homes. At first, Benoit is hesitant, unable to unpack his suitcase due to the fear of being rejected. Yet, he is joyfully enveloped by the warmth and affection that his new family provides. In time, Benoit finds the courage to ask his adoptive father, Bill, to change his name to Billy.
As Billy begins to settle into his new life, Channe finds herself leaning on her steadfast Portuguese nanny, Candida, to navigate the challenges of growing up. Initially, Channe is envious of her new brother, but that jealousy quickly transforms into affection when she invites him to share her bed following a minor mishap. Marcella takes a courageous stand against a strict teacher mistreating her son, while Channe starts to notice the cultural contrasts around her, from the rowdy American visitors who flood the city to the lively circle of friends surrounding her parents.
As the years roll on and they enter their teenage phase, Billy and Channe strengthen their sibling bond. Channe cultivates a close friendship with Francis Fortescue, a flamboyant young man passionate about opera. Despite his lack of a father figure, Francis lives with his quirky expatriate British mother, providing Channe with guidance as she explores her own independence. Simultaneously, Candida faces her fears when her partner, Mamadou, proposes marriage, prompting personal reflection. Meanwhile, as Channe begins to show interest in boys, she finds herself emotionally distancing from Francis, who reveals his secret crush on her.
The family's once-idyllic existence in Paris is jolted when Bill announces plans to move back to the United States for medical treatment concerning his heart condition. This significant decision propels them into a new reality, forcing them to confront the possibility of leaving behind the vibrant culture and city life that have been woven into the fabric of their identity.
As the 1970s unfurl over the picturesque hills of New England, uncertainty clouds their tranquil lifestyle. Bill's declining health looms large, alongside Marcella's struggle with alcoholism, which threatens to unravel the delicate equilibrium they have maintained. In this tumultuous environment, Channe and Billy navigate the challenges of an American high school, where bullying plagues shy Billy, who feels increasingly isolated. In contrast, Channe adopts a more assertive approach, venturing into fleeting romantic encounters. However, her world shifts when she meets Keith, a fellow free spirit who captures her heart.
Amidst the whirlwind of family dynamics, Bill immerses himself in a new literary venture while grappling with worries about leaving a legacy that does justice to his loved ones. The topic of Billy’s adoption, once a proud chapter, now becomes a source of unrest due to a mysterious diary penned by his biological mother during her teenage years. Although Billy has always been curious about his roots, it is only after Bill's passing that he discovers the chance to explore his origins. In a moment of vulnerability, Marcella hands the diary to Billy, hoping it serves as a bridge to solace and understanding in their shared grief. Yet, Billy finds himself more focused on strengthening his bond with his grieving mother rather than delving into the past.
As weeks pass and emotions ebb and flow, Channe gravitates back to the written word, assisting her father in finalizing his novel leading up to its release. During their healing journey, the family unites one evening, letting music fill the air as they dance together. In a moment of curiosity, Billy glances at the diary that has been waiting for the right moment, unaware that it is destined to play a pivotal role in his journey of self-discovery.
