Katarina “Kate” Andrich, a young aspiring singer, works a dead-end job as an elf at a year-round Christmas shop in Central London, whose strict but good-hearted owner calls herself “Santa”. Kate is homeless after being forced out by her new lover’s partner. While at work, she notices a man outside staring upwards and talks to him, learning that his name is Tom Webster.
After an unsuccessful singing audition, Kate sees Tom again and they go for a walk, where he charms her with his unusual observations of London. Upon isolating herself from her oldest friend, Kate is forced to return to live with her parents, both Yugoslavian immigrants. Her mother Petra suffers from depression, and her father Ivan, a former lawyer, works as a minicab driver as he cannot afford to retrain to practise law in the United Kingdom. Kate feels suffocated by her mother, who dotes on her while ignoring Kate’s sister, Marta, a successful lawyer who is closeted to their parents.
Kate begins spending more time with Tom, who rides a bike and volunteers at a homeless shelter, which she initially mocks. Looking for Tom, who says he keeps his phone in a cupboard and often disappears for days at a time, she begins helping at the shelter in the hope of running into him, but finds that the staff have never met him.