In 1912, Wilfrid Voynich, an antiquarian book dealer, stumbled upon a strange volume, its vellum pages covered in a beautiful but unrecognisable script accompanied by equally mystifying pictures. The codex has remained undeciphered from that day to this. Voynich believed the codex to be the work of medieval philosopher Roger Bacon, others that of the Elizabethan mathematician and occultist John Dee. Whoever created the book—which now resides at Yale University—it remains to this day a singular enigma which continues to defy the best efforts of linguists, cryptologists, and scholars. With the benefit of the authors' exhaustive research, readers can hazard their own guesses as to the meaning and provenance of this most beguiling of mysteries.