Grace is a 45-year-old linguist and former television personality experiencing a profound crisis of identity. Having recently lost her jobs as an assistant teacher and translator, she is struggling to manage severe perimenopausal symptoms alongside her grief over a past family tragedy. When she abandons her car in gridlock traffic, it marks the beginning of a desperate, erratic trek across the city to deliver an expensive "Love Island" cake to her estranged daughter, believing the gesture will repair their fractured relationship.

Lotte is Grace and Ben's 16-year-old daughter. Reeling from the unspoken trauma of her younger sister's death and her parents' recent separation, Lotte has grown secretive and hostile toward her mother. She currently lives with her father and acts out through truancy, social media obsession, and boundary-crossing behavior, demanding independence while quietly longing for parental stability.

Ben is Grace's estranged husband and a university academic. He recently left the family home and filed for divorce, taking Lotte in when her relationship with Grace collapsed. While he strives to act as a peacemaker and steady presence for his daughter, his own methods of coping with family tragedies involve evasion and seeking outside validation.

Nate is a young, handsome teacher at Lotte's school. He uses his charm and position of authority to manipulate the boundaries between himself, his students, and their parents. While he initially presents himself as an understanding ally to Grace regarding Lotte's truancy, he uses this trust to facilitate a predatory relationship with his teenage student.

Bea is Grace and Ben's second daughter, who died in a pedestrian accident at a young age. Though physically absent in the narrative present, her death serves as the foundational trauma that broke her parents' marriage and alienated her older sister. Her memory haunts Grace's every step across London.

Grace's sister, who currently resides in Los Angeles. She attempts to mediate the family's disputes from afar, maintaining contact with both Ben and Grace. She frequently offers unsolicited advice on raising teenagers, drawing from her own difficult experiences with her son's substance abuse.

Ben's mother. She has a highly abrasive, toxic personality that creates immediate friction when Grace visits Ben's childhood home. Her rudeness prompts early conflicts between Ben and his family.

Ben's former girlfriend from before his relationship with Grace. Because they work in similar academic and professional circles, they frequently cross paths at conferences, creating an avenue for Ben to escape his troubled home life.

The head teacher at Lotte's school. He attempts to manage Lotte's escalating behavioral problems by calling meetings with her parents and recommending counseling, though his administrative approach often frustrates the family.

A chatty mother involved in the local PTA. She inadvertently stalls Grace during her urgent walk across London. Finding Grace's behavior erratic and concerning, Freja later texts Ben to warn him about his wife's condition.