The book investigates the historical suppression of evidence and information regarding UFO phenomena by governments and official bodies. Nick Pope, a former UFO investigator for the British Ministry of Defence, draws upon his unique experience and access to classified documents to present a case for a deliberate, long-term cover-up. The work scrutinizes official reports, witness testimonies, and declassified files to expose patterns of disinformation and secrecy surrounding unidentified aerial phenomena.

The book is generally regarded as a significant contribution to UFO literature, particularly due to the author's insider perspective. Pope's background lends credibility to his claims of government secrecy and the systematic suppression of evidence related to unidentified aerial phenomena. Readers often cite the detailed case studies and the author's direct involvement as compelling evidence for his thesis. The work is frequently recommended for those interested in the intersection of UFOs, national security, and official cover-ups.