Cuando están a punto de graduarse en la prestigiosa Universidad de Princeton, dos estudiantes se ven envueltos en el enigma de Hypnerotomachia Poliphili, un libro publicado en 1499 que ha tenido en vilo durante muchos siglos a los expertos e investigadores de todo el mundo. Este libro de título impronunciable, es el núcleo en torno al cual gira `El enigma del cuatro`, y por el que el protagonista principal, Tom Sullivan, y sus amigos, empiezan a obsesionarse. Tom tiene el precedente en su padre, un estudioso del Renacimiento italiano que dedicó toda su vida a la investigación del enigma y que murió repentinamente en un accidente de coche. Arriesgando su relación sentimental con Katie y también su propia integridad, Tom se deja llevar por la pasión que el libro ha inferido a tantos estudiosos que han intentado, hasta ahora en vano, descifrar sus claves

Princeton. Good Friday, 1999. On the eve of graduation, two students are a hairsbreadth from solving the mysteries of the Hypnerotomachia Poliphili, a Renaissance text that has baffled scholars for centuries. Famous for its hypnotic power over those who study it, the five-hundred-year-old Hypnerotomachia may finally reveal its secrets-to Tom Sullivan, whose father was obsessed with the book, and Paul Harris, whose future depends on it. But as the deadline looms, research has stalled-until an ancient diary surfaces. What Tom and Paul discover inside shocks even them: proof that the location of a hidden crypt has been ciphered within the pages of the obscure Renaissance text. Armed with this final clue, the two friends delve into the bizarre world of the Hypnerotomachia—a world of forgotten erudition, strange sexual appetites, and terrible violence. But just as they begin to realize the magnitude of their discovery, Princeton's snowy campus is rocked: a longtime student of the book is murdered, shot dead in the hushed halls of the history department. So begins a cycle of deaths and revelations that will force Tom and Paul, with their two roommates, into a fiery drama spun from a book whose power and meaning have long been misunderstood. A tale of timeless intrigue, dazzling scholarship, and great imaginative power, The Rule of Four is the story of a young man divided between the future's promise and the past's allure, guided only by friendship and love. Suspenseful, passionate, and wise, it is certain to propel Ian Caldwell and Dustin Thomason to the forefront of contemporary fiction