Kohler calls Vetra's adopted daughter Vittoria home and it is ascertained that the Illuminati, an ancient anti-religious organization thought extinct, have stolen a canister containing antimatter, a substance with destructive potential comparable to a nuclear weapon. Plot ĬERN director Maximilian Kohler discovers one of the facility's top physicists, Leonardo Vetra, murdered, his chest branded with an ambigram of the word ' Illuminati.' Kohler contacts Robert Langdon, an expert on symbology, who determines that the ambigram is authentic. The 'Illuminati Diamond' mentioned in the book is an ambigram of the four elements that are arranged in the shape of a diamond. The book also contains ambigrams of the words Earth, Air, Fire, and Water, which has served to bring the art of ambigrams to public attention by virtue of the popularity of the book. Besides the 'Angels & Demons' and ' Illuminati' designs, the title of the book is also presented as an ambigram on the hardcover book jacket (see illustration at right on this page), and on the inside cover of the paperback versions.
The book contains several ambigrams created by real-life typographer John Langdon.
