The film opens with Tom eating with his family. He drives to Birmingham, boards the London train, and spends the day wandering through the city before finally sleeping outside a shop. In the morning, he discards his phone in a lake and bins his bank cards, keeping only a family photo as a fragile tether to the past while he pockets the remaining money.
That night, after a drink in the park, he is attacked by a gang of youths; when he tries to flee, he crashes into a tree and injures himself. The next morning, while waiting in A&E, Aidan behaves disruptively and then begins talking to Tom before Tom is called for examination. When Tom leaves, Aidan follows him.
Walking together, Aidan goes to urinate, and Tom, sensing an opportunity to escape, flees. He spots a couple having sex but immediately runs into Aidan again. Still determined to shake him off, Tom faints outside Aidan’s flat, and Aidan invites him inside and offers a beer. Linda—Aidan’s so‑called girlfriend—arrives home, startling Tom, whom he has just seen with her, and she is displeased that Aidan has earned little money. She punches him and tells him to throw Tom out. Tom leaves to buy tea, but returns when he discovers his pocket is empty, only to be met with Linda’s denial of knowledge and a smug smile as he departs.
After begging for change, Tom buys tea in a café. Aidan arrives with a cat carrier and offers to help with mouse-catching. The shop manager leads him to the back and attacks him. Tom hears the commotion, checks his health, and watches as Aidan realizes the elderly neighbour’s cat is missing. They locate the cat’s corpse and, in a strange gesture of care, buy a kitten for the owner, who yells at them to leave.
Aidan then shows Tom a drum kit he is saving for, dreaming of fame. Tom tells him to leave him alone, admitting he cannot cope with people—including his own family. Depressed, Tom pulls out the family photo and finds a bank card, which he uses to withdraw cash. He returns to Aidan’s flat, apologizes, and asks to stay, offering £200. Aidan tells Linda that Tom has paid £100, keeping the rest to fund his drum kit, and they celebrate. Yet, drunk, Aidan confesses to Linda that he actually received £200 and is saving toward a drum kit. Linda realizes Tom is “Mr. Moneybags” and, in a disturbing moment, masturbates him.
The next day, Aidan takes Tom to the Horniman Museum where they enjoy making music with public instruments. Aidan later withdraws his savings but is seen by a man who may be following him; as he walks home, the man mugs him. Tom asks for a description and realizes the mugger was Linda’s sexual partner. Linda returns home with designer clothes, and, allergic to cats, finds the kitten hidden in the wardrobe and attacks Aidan. When Tom protests, Linda threatens him with retaliation by her gangster friends. Tom then menaces her with a knife, grabbing her by the throat and demanding she confess to stealing the money. Frightened, she has an asthma attack; Aidan grabs for her inhaler, but it falls under the fridge. With Linda unconscious, they eventually recover it. Aidan kicks her out permanently, enduring her abuse in silence.
Aidan goes to the shop to see the drum kit, only to find it has been sold, which greatly upsets him. He returns home to discover Tom has gone, heightening his distress. Entering his bedroom, he finds the kit Tom has bought for him. The film ends with Aidan drumming and Tom walking to a train station, boarding and taking the train home.
