When Foreign Office civil servant Samuel Fennan commits suicide after a routine security check by "the Circus" (so called because of its location in Cambridge Circus‚ and apparently based on MI6)‚ Smiley is sent to investigate. Smiley had interviewed and cleared Fennan only days previously after an anonymous accusation of Fennan's membership of the Communist Party while at Oxford University; however‚ head of service Maston believes that Smiley must be to blame for the suicide.