Martin is a middle-aged former morning television personality. He loses his career, his marriage, and his public standing following a scandalous affair with a fifteen-year-old girl. Feeling that his life is ruined by his own bad decisions, he goes to the roof seeking an end to his public humiliation.

Jess is an eighteen-year-old dealing with mental health struggles and a chaotic personal life. She arrives on the roof after her boyfriend breaks up with her without explanation. She is highly impulsive, struggles with anger, and feels deeply abandoned by those she cares about.

JJ is a twenty-six-year-old American living in London. He works as a pizza deliveryman after the dissolution of his band and his romantic relationship. He feels intensely inadequate and struggles to see a future for himself without music, believing that a normal job is intolerable.

Maureen is a fifty-one-year-old single mother who serves as the full-time caregiver for her severely disabled adult son. She lives an isolated life devoid of friends or leisure, feeling suffocated by her daily responsibilities. She views her difficult life as a divine punishment for a past sin.

Matty is Maureen's adult son. He has severe physical disabilities and requires constant, demanding care. He spends most of his time at home with his mother or occasionally stays overnight at a specialized care facility.

Chas is Jess's former boyfriend. He ends their relationship without providing an explanation, prompting her desperate search for closure on New Year's Eve. He views Jess as unstable and avoids her completely.

Cindy is Martin's ex-wife. She lives in Torley Heath with their two daughters. Following Martin's public scandal, she establishes strict boundaries, refusing to let him visit the children at her home.

Penny is a young television personality who formerly co-starred on a morning show with Martin. She maintains a complicated relationship with him after his career collapses, struggling to deal with his self-loathing moods.

Jen is Jess's older sister who disappeared years earlier after abandoning her car near a known suicide spot. Her absence leaves a profound sense of loss and unresolved grief in her family.

Eddie is JJ's close friend and a former member of their band, Big Yellow. He secures a job installing cable after the band breaks up, adjusting to normal life much faster than JJ.

Lizzie is JJ's former girlfriend. She ends their relationship shortly after his band dissolves, recognizing that he will be miserable without his music.

Chris is Jess's father and a government education minister. He is overwhelmed by his daughter's unpredictable behavior and tries to enlist Martin's help in keeping her safe.

Theo is Martin's literary and talent agent. He was promoted to the position from an internship while Martin was in prison, demonstrating Martin's diminished status in the entertainment industry.

Linda is an aggressive tabloid reporter. She investigates the four people seen together on the roof of Toppers' House. She pays for exclusive interviews to exploit their story for her readers.

Frank is Maureen's former fiancé and the father of her son. Maureen claims she ended the relationship because he did not love her enough, choosing a life of isolation instead.

Stephen is a handsome orderly who works at the respite home where Matty occasionally stays. He is kind and attentive to Maureen and her son.

Pacino is an eight-year-old boy who struggles with reading. He loses focus quickly during lessons, providing Martin with a challenging but necessary test of commitment.

Nodog is a man Jess meets by the water. He leaves his dog outside of bars, earning him his nickname from Jess. He offers her philosophical advice about viewing reality without embellishment.