Civil engineers Graham Harris and Les MacPhie have spent over a decade investigating the enigma of Nova Scotia#146;s Oak Island. In this new edition of their book, they set out the previously unknown story of how complex and expensive engineering work was undertaken to create an elaborate flood tunnel on the island. Built to frustrate treasure seekers attempting to get at the valuables buried decades earlier at the bottom of the island#146;s Money Pit, the tunnel has admirably served its purpose. It has ensured that all efforts up to now to recover the treasure have been unsuccessful. Oak Island poses two different challenges for treasure seekers. There is a deep mine shaft, at the bottom of which the treasure lies. The authors offer evidence that this treasure came from the wreck of a Spanish galleon in the seventeenth century. Even more mystifying than the mine shaft is the complex tunnel which links it to the ocean. Harris and MacPhie have determined that the project would have required a labour force of over 100 men to supplement a small force of experienced miners. The work would have taken almost two years to complete. In new chapters written for this edition, they present the evidence they have discovered in British military history records which shows who commanded this force, how it reached Nova Scotia, and when the work was carried out. The new facts and insights offered in this book are a startling and convincing addition to the history of Oak Island.