Set in 1993 London, About a Boy features two main protagonists: Will Freeman, a 36-year-old bachelor, and Marcus Brewer, a 12-year-old incongruous schoolboy described as "introverted" by his suicidal mother, Fiona, despite his tendencies to bond and interact with people.

Will's father wrote a successful Christmas song, the royalties of which have afforded Will the ability to remain voluntarily redundant throughout his life – he spends his plentiful free time immersing himself in 1990s culture, music, and pursuing sexual relations with women.

Although their relationship is initially somewhat strained, they finally succeed in striking up a true friendship despite Will being largely uninterested during the early-middle stages of the novel.

Will, a socially aware and "trendy" person, aids Marcus to fit into 1990s youth culture by encouraging him not to get his hair cut by his mother, buying him Adidas trainers, and introducing him to contemporary music, such as Nirvana.

Marcus is befriended by Ellie McCrae, a tough, moody 15-year-old girl, who is constantly in trouble at school because she insists on wearing a Kurt Cobain jumper.

The penultimate scene takes place in a police station in Royston (a small suburban town), where nearly every significant character in the novel is present, their common link being Marcus.

The film received positive reviews from critics, was nominated for an Academy Award for Best Adapted Screenplay, and earned $130,549,455 at the box office against a $30 million budget.