The story is told out of chronological order but mostly follows the upper-class Englishman Adrian Healey through his years at public school, at Cambridge University, and afterwards.

Adrian claims to have run away from home due to unhappiness, subsequently becoming a rent boy, but it is later revealed, in an overheard conversation, that this probably never occurred.

Eventually, Adrian takes on the role of schoolmaster and has his first sexual encounter with a woman, a fellow member of staff at the school.

Adrian attends the fictional St. Matthew's College, Cambridge and is given a challenge to produce something original by his tutor Professor Donald Trefusis.

With the aid of his girlfriend – and later wife and acclaimed producer – Jenny de Woolf, and his housemate Gary, he writes and claims to have discovered a lost manuscript by Charles Dickens which dealt with the child sex trade.

It is later revealed that he was actually undertaking a document exchange preceded by two kisses on the cheek as is custom in several European countries, such as Hungary.

In actuality, the year is spent in a game of espionage in which they must acquire the parts for Mendax (from the Latin adjective meaning "lying, deceptive"), a lie-inhibiting device from his Hungarian friend Szabó.

Subsequently, Adrian overhears a conversation between Trefusis and Pearce where it is revealed that the espionage adventure was just a game to counter boredom, meaning that several parts of the story were untrue.