It Starts With Us tells the story of Lily Kincaid and Atlas Corrigan, two high school sweethearts who are fatalistically reunited after being separated by domestic abuse and homelessness as teens. The story picks up where It Ends with Us, the first novel in the duology, left off with a chance run-in on the streets of Boston. The couple considers how their second-chance romance might develop as Lily is struggling with concerns about her abusive ex-husband, Ryle, who is violently jealous of Lily’s connection to Atlas. Throughout the novel, Lily extricates herself from Ryle’s manipulation and control as she develops a healthy relationship with Atlas. Meanwhile, Atlas struggles against his abusive and neglectful mother Sutton to save his twelve-year-old half-brother, about whom he just found out, from the same kind of abuse he suffered as a child. Together, with love, compassion, and community, both Atlas and Lily disentangle themselves from the toxicity of their abusive pasts and strike out to create a new family model. 

The inciting incident occurs at the end of It Ends with Us when Atlas and Lily meet on the street and profess their intention to rekindle their romance. In the giddy afterglow of that meeting, Atlas and Lily both have problems to solve that are related to their abusive pasts. Atlas’s restaurants are being vandalized by a mystery teen, and though Atlas doesn’t know the boy is his half-brother Josh, he feels protective and empathetic for the vandal’s situation, which is reminiscent of Atlas’s own adolescence as an abandoned teen experiencing houselessness. Meanwhile, Lily struggles to even engage with the possibility of a romance with Atlas, concerned and frightened about Ryle’s potentially explosive response. Lily frets about how Ryle’s rage and jealousy will impact their infant daughter, Emerson. In this way, though they’re divorced, Ryle still has control over Lily. The growing romance between Atlas and Lily, the quest to save Josh from Sutton’s destructive hands, and the escape from Ryle’s dominance are the three primary plot lines braided throughout the novel. 

The story is told in alternating first person perspectives between Lily and Atlas. The novel’s telling also moves back and forth between the past and the present, interweaving Lily’s diary entries, which are addressed to Ellen DeGeneres, and Atlas’s letters to Lily, both of which offer accounts of Lily’s and Atlas’s experiences as teens when they were first falling in love and struggling with their abusive parents. In her teenage diary entries, Lily recounts both the first blush of love with Atlas and the heartbreaking violence of her father. As Atlas reads through these journal entries, he gets to relive their first romance and understand the girl he loved more deeply. He is inspired to bring Lily into the parts of his story she didn’t know the first time they were together. In reading Atlas’s letters, Lily understands how much Atlas suffered, how much he protected her from his pain to spare her feelings, and how much her love meant to Atlas. By reliving the past together, Lily and Atlas support each other through healing the pain of the past and nurture the love grows between them in the present. 

The rising action occurs when Atlas and Lily go on their first date, which is followed by Sutton’s appearance and Ryle’s first enraged outburst. On the date, Lily falls asleep, and Atlas let’s her get the rest she needs while reading through her teenage journal, which she brought as a gift for him. This illustrates Atlas’s thoughtfulness, as he’s content to simply sit with Lily while she gets what she needs, along with Lily’s generosity, sharing herself with Atlas even though she finds the process of him reading her journals a bit embarrassing. After the sweet date, the work both characters have to do to escape their violent pasts immediately emerges. Lily faces the irate Ryle, who discovered that Emerson’s middle name honors Dory in Finding Nemo, a movie that has significance for Lily and Atlas. In stark contrast to Atlas’s consideration and kindness, Ryle behaves with jealousy, petty threats, rage, and gaslighting, which further confuses Lily and makes her doubt herself, emphasizing that she still has work to do to escape Ryle’s clutches. At the same time, Atlas finds himself face to face with his mother for the first time since he was a teenager and learns that he has a younger brother who is missing. Atlas suspects his brother is the vandal and feels immediately protective of him. Like Lily, Atlas is faced with echoes of his violent past and an opportunity to do something differently this time around. 

The climax of the novel occurs when Lily and Atlas make love for the first time and Ryle violently attacks Lily, and later, Atlas. These experiences are stark reminders for Lily, both of the gentleness, tenderness, and love she feels for Atlas, and the terror, violence, and confusion she still feels with Ryle. For Ryle, Atlas and Lily beginning a romantic relationship is a confirmation that all his jealousy was grounded in reality. Instead of taking responsibility for his violent actions, Ryle blames Atlas for both his marriage failing and the current acrimony he’s experiencing with Lily. In contrast, Atlas fights against his own anger, taps patience and compassion to counter Ryle’s attacks, and argues that he, Ryle, and Lily all need to work together for Emerson’s sake. While Ryle embodies Lily’s past—both the terror of their marriage and the pain of her childhood with her abusive father—Atlas embodies her future, one in which love takes the place of toxicity and her well-being and the well-being of her daughter take center stage. 

In the falling action, Atlas confronts Sutton, while Lily, Marshall, and Allysa confront Ryle. In each conversation, the characters demand that the abuser take responsibility and set firm boundaries that leave no room for argument or negotiation. Atlas shows Sutton both compassion and firmness by making her favorite food and by demanding custody of Josh, as this is what is in his brother’s best interest. Sutton reluctantly accepts both the terms of Atlas’s custody proposal and the coconut shrimp he cooks for her, illustrating that she may be willing to act differently toward her sons in the future. Meanwhile, Lily, Marshall, and Allysa present a united front to Ryle, staging an intervention and demanding that he get treatment for his anger. By working together and by protecting his daughter and niece, the three demonstrate that they will no longer allow Ryle’s rage and violence to harm Lily or the children. Together, Atlas and Lily, with each other’s support and the support of family, take a clear stand. The family they build together will no longer be dominated by violence but instead will be guided by compassion, tenderness, and love.