1953. A London shattered by WWII is still recovering. Williams (Bill Nighy), a veteran civil servant, is an important cog within the city's bureaucracy as it struggles to rebuild. Buried under paperwork at the office, lonely at home, his life has long felt empty and meaningless. Then a shattering medical diagnosis forces him to take stock – and to try and grasp fulfilment before it goes beyond reach. At a seaside resort, chaperoned by a local decadent (Tom Burke), he flirts with hedonism before rejecting it as his solution. Back in London he finds himself drawn to the natural vitality of Margaret (Aimee Lou Wood), a young woman who once worked under his supervision and is now determined to spread her wings. Then one evening he is struck by a revelation – one as simple as it is profound – and with a new energy, and the help of Peter (Alex Sharp), an idealistic new recruit to his department, he sets about creating a legacy for the next generation.