Book excerpt: In this illuminating companion to Dan Brown's Inferno, historian Michael Haag sets out the truth behind the novel's myths, mysteries and locations. How do the clues unveiled in symbology professor Robert Langdon's daring quest from Florence to Venice and Istanbul overlap with history? What codes and symbols did Dante employ in the Divine Comedy and which secret religious, philosophical, and scientific themes are hidden within his work? What lies behind Botticelli's Mappa dell'Inferno? And what are the cult scientists known as transhumanists really up to? Inferno Decoded is a book that ranges as widely as Dan Brown's novel, from the terrors of the Black Death to the scientific debates around population growth and prolonging of life-spans, and from the economic, political, and religious tumult in Florence at the dawn of the Renaissance to real-life locations in Florence, Venice and Istanbul today. It is a must-read for anyone who has read Inferno and wondered just how its enigmatic questions are real or relevant.