The book investigates the vast and intricate network of the international Sicilian Mafia, known as 'Octopus'. Claire Sterling, an investigative journalist with extensive experience covering international crime and politics, draws upon years of research, interviews, and leaked documents to expose the Mafia's deep infiltration into global finance, politics, and illicit trades. The work aims to map the structure and influence of this powerful criminal organization, detailing its operations from drug trafficking and arms dealing to its connections with corrupt officials and international agencies.

Claire Sterling's 'Octopus' is recognized as a seminal work in the study of organized crime, particularly the Sicilian Mafia. Critics and readers have noted its meticulous research and the author's ability to connect disparate pieces of information to form a comprehensive picture of the Mafia's international operations. The book is often cited for its detailed exposé of the organization's financial dealings and its insidious influence on global politics. Its enduring relevance lies in its thorough documentation of how criminal enterprises can extend their reach far beyond local boundaries.