Seventeen-year-old Ben Marshall is the sensitive son of a complacent vicar, Robert, who is obsessed with ornithology, and a domineering mother, Laura, who performs numerous charitable acts while ignoring her family’s emotional needs. She even forces Ben to deliver meals on wheels despite him not having a car. Despite her strong religious beliefs, Laura conducts an affair with Peter, a young curate who plays Jesus in the church pageant she is directing.
Laura’s grip on Ben extends to his social life, denying him a mobile phone and keeping him away from peers. She uses his driving lessons to shuttle him around for her affair, while Ben, left to navigate his own feelings, writes poems for Sarah, a girl he knows from church. When he reads her his latest “Sarah Poem,” she rejects him, underscoring the loneliness of his adolescence.
At his mother’s urging, Ben seeks summer work to help support Mr. Fincham, a mental patient Laura has adopted. He answers an ad placed by Dame Evie Walton, an alcoholic, classically trained actress whose career faded and who now appears on a daytime soap. Evie, in need of companionship and a driver, immediately takes to Ben and hires him.
Laura initially refuses a camping trip with Evie, but the two instead plan a country-drive excursion. On a secluded spot, Laura secretly swallows the car key, leaving Ben stranded with her. The next morning, she declares they must drive to the Edinburgh International Book Festival, where she is invited to read poetry. What begins as a road trip turns into a turning point for Ben: he experiences his first sexual moment with Bryony, one of the young women helping organize the festival. Through this encounter, Ben discovers the importance of responsibility and the strength to stand up for himself.
Returning home, Ben faces intense questioning from Laura, who suspects Evie has corrupted him. Evie visits, but Laura rebuffs her. In a fit of resolve, Ben leaves the pageant backstage, bikes to Evie’s house, and the two friends reconnect.
Evie’s arrival at the Pageant, where she portrays God, inflames the crowd into a frenzy, and Ben slips into the car park to join her. Laura pursues them and attempts to weaponize the Bible once more, but Ben tells her to go away. The tension culminates in tragedy as Laura is run over by Mr. Fincham, whose mental state has deteriorated.
In the hospital, Laura claims a near-death experience has made her a prophet and that God instructs her to divorce Robert and run off with Peter, who has been fired by the Bishop and takes Laura to Cornwall to convalesce.
Ben’s confrontation with reality intensifies when he runs into Sarah, who coolly remarks that the affair was God’s will. He finally speaks his mind, telling her to “fuck off.” On Evie’s advice, Ben buys a tent and moves to the backyard, while Robert reveals he had asked Laura for a divorce and had tried to stay faithful. The two men reconnect as Ben asserts his independence.
With a heart full of new possibilities, Ben tells Evie he plans to move to Edinburgh to study English. Evie expresses quiet happiness for his future, even as she laments losing his day-to-day presence. He reads her a final poem in which he thanks her for their friendship, and Evie replies with a proud smile. Ben promises to visit whenever he’s back from college.
The film closes with Ben, finally free, walking through a park on his way home to begin packing for Edinburgh, ready to begin a new chapter while carrying the lessons of his summer—from responsibility and self-respect to the strength found in choosing his own path.
