Willie Somerset Chandran is the son of a Brahmin father and a Dalit mother. His father gave him his middle name as a homage to the English writer Somerset Maugham who had visited the father in the temple where the father was living under a vow of silence. Having come to despise his father, Willie leaves India to go to 1950s London to study. There he leads a life as a poor immigrant and later he writes a book of short stories and manages to publish it.
Willie receives a letter from Ana, a mixed Portuguese and black African girl, who admires his book, and they arrange to meet. They fall in love and Willie follows her to her country (an unnamed Portuguese colony in Africa, presumably Mozambique). Meanwhile Willie's sister Sarojini marries a German and moves to Berlin. The novel ends with Willie having moved to his sister's place in Berlin after his 18 year stay in Africa.
Half a Life is a precursor to Naipaul's 2004 novel Magic Seeds which starts with Willie in Berlin.