Foucault's Pendulum

The plot of Foucault's Pendulum revolves around three friends, as relevant to the rule of three, named Belbo, Diotallevi and Casaubon, who work for a vanity publisher in Milan. After reading one too many manuscripts about occult conspiracy theories, they decide they can do better, and set out to invent their own conspiracy for fun. They call this satirical intellectual game "The Plan". As Belbo, Diotallevi and Casaubon become increasingly obsessed with The Plan, they sometimes forget that it's just a game. Worse still, when adherents of other conspiracy theories learn about The Plan, they take it seriously. Belbo finds himself the target of a very real secret society that believes he possesses the key to the lost treasure of the Knights Templar. It's a tough read with numerous plots twists and endless references to societies that I must separately research. Oh, and then there's the translating from Italian.