Rodney Williams is a dedicated bureaucrat working for the London County Council in the year 1953, feeling overwhelmed as he sits amidst towering stacks of paperwork, his inspiration seemingly depleted. A group of determined women, led by Mrs. Smith, approach the council with a heartfelt petition, seeking to transform a World War II bomb site into a children's playground. However, their request is met with indifference, as the petition is shuffled from one department to another without any real consideration. When the petition ultimately lands on Mr. Williams' desk, he adds it to his ever-growing pile, signaling to his colleagues his intention to take no meaningful action.
In a tragic turn of events, Mr. Williams learns of his terminal cancer diagnosis, yet he chooses to keep this news a secret from his son, Michael, and daughter-in-law, Fiona. Instead, he takes a drastic step, withdrawing half of his life savings and purchasing a fatal dose of sleeping medication with plans to end his life in a serene seaside resort. At the moment of decision, however, he finds himself unable to proceed with his plan and instead encounters Mr. Sutherland, an insomniac writer in a local restaurant, whom he gifts the sleeping medicine.
Moved by Mr. Williams' poignant story, Sutherland takes him out for a memorable evening. During their escapade, Williams trades in his traditional bowler hat for a stylish fedora. At a pub, he unexpectedly connects with his past, singing “The Rowan Tree,” a Scottish folk song that resonates deeply with his childhood. Upon returning to London, although he avoids returning to work, Williams has a chance meeting with Miss Harris, a former colleague now working at a restaurant. Their lunch together is noticed by a meddlesome neighbor, causing Fiona to demand that Michael confront his father about potential gossip.
As time goes on, Williams struggles to convey his diagnosis to Michael, with both father and son unable to breach the subject clouded by unspoken emotions. As his health deteriorates, Williams increasingly cherishes the company of Harris, whose youthful enthusiasm he longs to regain. Realizing that he wants to leave a positive mark on the world, Williams inspires his office to take action in constructing the children's playground that was once sidelined. He successfully advocates for the project, confronting his superiors to expedite the process, yet he tragically passes away shortly after its completion.
At his funeral, a heartfelt gathering of those he impacted, Michael speculates to Harris that his father may have confided in her about his condition, a revelation that leaves lingering questions. Motivated by Williams' legacy, his former colleagues vow to change their ways, but the pressures of their roles quickly lead them back to their old habits. Mr. Wakeling, a new recruit in the office, discovers a letter left by Williams encouraging him to remember the playground during tough times. A visit to the playground reveals a heartwarming encounter when a police officer recounts seeing Williams enjoy a moment of solace there just before he died, swinging in the snow and singing “The Rowan Tree.” The officer grapples with guilt for allowing Williams to sit outside in his fragile condition, but Wakeling reassures him that in that moment, Williams was likely experiencing greater joy than he had in a long time.
