In 1970, writer Alan Bennett (played by a thoughtful, introspective individual) makes the significant move to Camden's affluent suburbs. Here, he crosses paths with Miss Mary Shepherd, an enigmatic, eccentric, and often unkempt homeless woman who resides in a dilapidated Bedford van, squatting outside various homes on Gloucester Crescent. As her presence becomes a staple within the community, social workers frequently check on her, while neighbors occasionally offer her gifts or meals.
One day, the calm of Miss Shepherd's existence is disrupted by two unruly youths who inadvertently startle her, shaking her van and disturbing her from a vivid nightmare about a long-ago traffic accident. This unsettling encounter leads Alan to reflect on the well-being of this new acquaintance, ultimately suggesting that she park in his driveway. Although she is initially reluctant, a kind neighbor comes to their aid, providing a replacement van, allowing Miss Shepherd to stay in Alan's driveway for a remarkable length of time—15 years (1974-1989).
During these years, Alan navigates the challenges of his writing career while also attending to his increasingly frail mother. Despite his initial denial of any emotional connection to those around him, he starts to recognize the deep bond forming between him and Miss Shepherd. To his surprise, he discovers her surprising skill in French, a talent honed during her time as a piano student in Paris. This revelation sharply contrasts with her strong dislike for all music. When Alan inquires about her aversion, she shares a poignant memory from her brief time as a nun, where she was told never to play the piano after performing a classical piece.
As he digs deeper into Miss Shepherd's past, Alan uncovers a weaving story of unique experiences that include driving an ambulance during the 1939 blackout of World War II, performing Chopin at The Proms, and her two attempts to join a convent. Moreover, she reveals that her full name is Margaret Fairchild. A puzzling figure often appears at her van, causing her to feel uneasy, and she routinely gives him money.
Eventually, Alan seizes the chance to visit a day center that Miss Shepherd is relocating to, hoping to meet this mysterious visitor. He is taken aback to learn that this man is her brother, who recounts how he had once institutionalized her at Banstead, only to see her escape soon after. Additionally, he shares that she had studied with the esteemed pianist Alfred Cortot during her time as a nun.
Upon returning to his home, Alan finds Shepherd's van back in his driveway—a poignant reminder of their unique relationship. It becomes clear that Shepherd had run away from Banstead after an unsettling encounter with a familiar face and had taken refuge playing the piano at the community center. However, this brief escape was short-lived, as she confides in Alan about her confessor's warning that playing could hinder her spiritual journey.
As her van settles once again in Alan's driveway, an overwhelming sense of dread washes over him. Before he retreats indoors, Shepherd requests to hold his hand, which he complies with, sensing an urgent need in her gesture. Not long after this intimate moment, she peacefully passes away in her van, leaving behind a multitude of memories and stories left untold.
Her funeral is steeped in sorrow, highlighting the tragic nature of her final days; after being involved in an accident with a motorcyclist, she lived in fear of being arrested for the rest of her life.
In the following days, Alan finds comfort in writing, reflecting on the two-decade friendship he shared with Miss Shepherd by penning a memoir. This gives him the chance to explore the multifaceted life of a woman who constantly challenged societal norms.
As the film concludes, the real Alan Bennett watches with a sense of nostalgia as his younger self unveils a blue plaque commemorating "Miss M.T Shepherd, The Lady in the Van."
