How are the origins of the French Revolution, the murder of the Romanovs, the design of the dollar bill and the Roswell UFO incident connected? The answer is one of the world's most mysterious and feared secret societies - the Illuminati. References to the Illuminati span centuries, yet reliable historical evidence is scant.

What is known is that on 1 May 1776, at the height of the European Enlightenment, Adam Weishaupt, a professor of canon law at the University of Ingolstadt in Bavaria, founded a secret society of freethinkers, or 'enlightened ones' - the Illuminati. The group was formed to discuss and disseminate the radical philosophies of the day, and secrecy was crucial to its survival: neither church nor crown would have countenanced the group's anticlerical and antimonarchist ideas. At its height the Illuminati numbered 2,500, with members across Europe, including some of the period's leading thinkers. Yet just 12 years after the group's founding, it was disbanded by a governmental edict and the Illuminati ceased to exist.

Or did it? For nearly 250 years references to the Illuminati and its alleged influence on major world events have continued to resurface. There are those who claim the Illuminati is much older than its first recorded incarnation suggests, dating its origins to the time of the Pyramids, and others who believe the group is literally not of this planet but part of an alien culture bent on taking over the earth.

This book looks at the reality and the myths, questions the allegations and explores how fears about the group have taken many different forms, whether fear of intellectuals during the Enlightenment, or fear of communists during the McCarthy era. An internet search reveals that belief in the group's shadowy influence is positively thriving - what does that say about us today? And are we right to be afraid?