Eberlin, a double agent operating within British intelligence, receives the order to track down and eliminate a Soviet mole who is, in fact, himself. Eberlin navigates the rigid, bureaucratic landscape of Cold War London while attempting to sabotage the very investigation he has been tasked to lead. He faces the constant threat of exposure from his superiors in the British Secret Service and his handlers in Moscow. The narrative employs a detached, cynical tone to mirror the protagonist's internal isolation as he maneuvers through a web of deception. His objective is to maintain his cover while orchestrating his own escape from a tightening trap.

Readers and critics frequently note the book's stark, unsentimental approach to the spy genre. Discussion often centers on the protagonist's profound alienation and the bleak, clinical atmosphere that permeates the narrative. Many highlight the effectiveness of the central irony, which forces the reader to track the protagonist's movements from two opposing perspectives simultaneously. The pacing is described as deliberate and focused on psychological tension rather than overt action sequences. This work is often cited for its contribution to the subversion of traditional espionage tropes during the mid-twentieth century.