A high-stakes intelligence operation is compromised when a double agent is suspected of leaking classified information to the enemy. Protagonist Paul Grant, an operative within the British intelligence apparatus, must navigate a labyrinth of suspicion and betrayal to identify a mole known as 'Hangman.' He faces intense pressure from his superiors to secure the network while contending with the rigid, often opaque protocols of the Cold War era. The narrative utilizes a third-person perspective to track the shifting loyalties and tactical maneuvers of various intelligence officers. The story operates under the constraints of limited information and the constant threat of exposure in a world where trust is a liability.

Readers frequently highlight the clinical and grounded approach to the espionage genre found in this work. Discussion often centers on the author's ability to maintain suspense without relying on excessive action sequences. Critics note that the pacing reflects the slow, methodical nature of intelligence work during the mid-twentieth century. The character development is often praised for its focus on the psychological toll of constant suspicion. Many readers appreciate the intricate plot construction that keeps the identity of the antagonist obscured until the final stages of the narrative.