A young man named Wayne, new to London, asks Cyril, a man in his mid-thirties, directions to a block of flats where he claims his sister lives. Cyril invites Wayne up to his flat, which he shares with his partner, Shirley. Wayne explains that he has left his home in Byfleet after an argument with his mother and that his sister, Vivienne, has found him a job working on a building site. Cyril and Shirley advise Wayne to ask the local cab firm which street his sister lives on.

Cyril and Shirley visit Cyril's mother, Mrs Bender, who lives on her own in a council house. They make awkward small talk but Mrs Bender falls asleep in her chair. Wayne returns to the flat, having been unable to locate his sister. He stays the night.

Cyril's sister, Valerie, visits Mrs Bender. Valerie gives her mother a Christmas present - two months late - an instrument for checking blood pressure. When Valerie's husband, Martin, comes home from work that evening expecting his dinner on the table, Valerie presents him with a slice of bread and water.

When Mrs Bender arrives at the chemists to get her medicine, she realises that she has left her purse at home. She returns home to discover that her keys are also inside her purse. She solicits the help of her upper-class next-door neighbour, Laetitia Boothe-Braine, who reluctantly invites her into her house to wait for someone to bring her a spare set of keys. Some time later, Valerie arrives, but she has also forgotten to bring the keys. Valerie uses the Boothe-Braines' phone to call Cyril. Cyril and Shirley turn up with the keys and let Mrs Bender into her house.

Once again Wayne visits Shirley and Cyril. They take him to his sister's flat but she isn't at home. After waiting outside for a while, they put Wayne on a bus back to Byfleet. Cyril and Shirley go and play pool and, after some joking around back at home, Shirley expresses her desire to have a baby; Cyril is firmly opposed. Laetitia and her husband Rupert discuss their night at the opera, while Valerie and Martin lie in bed waiting for each other to make the first move.

The next day, Cyril and Shirley visit Karl Marx's grave. On the way home, they bump into an old friend, Susie, who they invite up to the flat. Susie's staunch anti-abortion beliefs provoke a lengthy socialist debate.

The following Sunday, Martin picks Mrs Bender up to take her to her 70th birthday party his and Valerie's house. On the way, he stops off to see his mistress. Explaining that he only has ten minutes, he tries to force himself on her and she pushes him away. Martin and Mrs Bender, Shirley and Cyril arrive at the house. At the table, Shirley gives Mrs Bender a shawl, while Valerie pretends that Harrods made a mistake with her order of a present for her mother. Valerie has a mini-breakdown and disappears from the table. Martin advises Cyril to secure his future financially and suggests that he start up his own business. Cyril explains that he is uninterested in material pursuits. Valerie reappears with the birthday cake, but when she tries to force-feed her mother a piece, a fight breaks out.

Shirley offers to escort Mrs Bender home in a cab but on the way she becomes disoriented and Shirley decides to take her home until she feels better. Cyril is against having his mother in his flat, but when Mrs Bender talks about how badly her mother treated her and begins to cry, he starts to soften. They let her stay the night. Cyril admits to Shirley that he should pay his mother more attention and the couple discuss their fears of growing old.

The next morning, Shirley and Cyril take Mrs Bender up to the roof terrace of their block of flats and point out places of interest. Now content, Mrs Bender settles into a chair, absorbing a 360-degree view of London's industrial skyline.