The play is based on Anthony Blunt's role in the Cambridge Spy Ring and, as Surveyor of the Queen's Pictures, personal art advisor to Queen Elizabeth II. It portrays his interrogation by MI5 officers, his work researching and conserving art works, his work at the Courtauld Institute, and his acquaintance with the Queen. While supervising the restoration of a dual portrait in which only partial attribution to Titian is thought credible, Blunt discovers a third figure that had been painted over by an unknown artist, and concludes by comparison with a better known triple portrait in London's National Gallery that the newly revealed third figure was Titian's son. As Blunt's public exposure as a spy in 1979 draws near, the play suggests that he has been made a scapegoat to protect others in the security service. At the end, the time of Blunt's exposure, Blunt tells Chubb that X-rays had revealed the presence of a fourth and fifth man.