A celebrated writer is recruited by the British Secret Service to operate in neutral Switzerland during the First World War, where he must navigate the moral ambiguity of espionage. Ashenden, a man of letters turned intelligence operative, finds himself tasked with monitoring enemy movements and managing sensitive assets across Europe. His objective is to maintain his cover as a playwright while executing clandestine missions that often conflict with his personal sense of morality. The narrative framework consists of a series of interconnected short stories that follow Ashenden through various assignments, highlighting the logical constraints of a world where information is currency and betrayal is a standard operational procedure. He faces opposition from both enemy agents and the cold, bureaucratic indifference of his own handlers.

Readers and critics frequently highlight the work's departure from the romanticized tropes of spy fiction common in the early 20th century. Discussion often centers on Maugham's ability to balance the inherent danger of the protagonist's missions with a dry, observational wit that underscores the absurdity of war. Many note that the stories prioritize character psychology and the ethical dilemmas of the agent over high-octane action sequences. The collection is often praised for its authentic tone, which stems from the author's own background in intelligence. Readers appreciate the subtle pacing and the way the narrative captures the cold, often unglamorous reality of life as a secret agent.