The Hiram Key (1996), co-authored by Christopher Knight and Robert Lomas, was an instant bestseller and has now been translated into 37 languages, selling over a million copies worldwide. Alan Butler, an engineer with a passion for history, also studied astrology and astronomy. He has authored four successful books about the Knights Templar and the Grail tale, based on his research into ancient cultures, pagan beliefs, and comparative religion. They are co-authors of Civilization One, Who Built the Moon?, and have a reputation for thoroughly researching and questioning hypotheses on early history.