The Rule of Four

Endeavoring to decipher a five-hundred-year old text that weaves a mathematical labyrinth within a love story, researchers Tom Sullivan and Paul Harris obtain a diary that may contain the key to the code, but when a fellow researcher is killed, they realize that the book contains a dangerous secret. 100,000 first printing.

Ian Caldwell is the author of a forthcoming novel set inside the Vatican. He graduated Phi Beta Kappa in European history from Princeton University, and lives near Washington, D.C., with his wife and three sons. Dustin Thomason is also the author of 12.21. He graduated from Harvard College and received his M.D. from Columbia University. Thomason has written and produced several television series, including Lie to Me. He lives in Venice Beach, California. The two have been best friends since they were eight years old.