On September 23, 1909, the Parisian daily newspaper, Le Gaulois, published its first installment of Gaston Leroux's Le Fantôme de l'Opéra (The Phantom of the Opera). This type of serialized publication, in France called a “feuilleton,” was common from the middle of the 19th century through the beginning of the 20th century. Many authors of the day published their novels section by section in newspapers to gain readership and to work out ideas before the publication of the first edition. Between the newspaper printing and the first edition, it was common for chapters to be added, rewritten, or removed as part of the editing process. In the feuilleton of Le Fantôme de l'Opéra, Gaston Leroux wrote a chapter called “L'enveloppe magique” (“The Magic Envelope”). Leroux decided to omit this chapter from his first edition, and so it only appeared in Le Gaulois. Since the feuilleton has never been translated, few people apart from the most dedicated Phantom enthusiasts are familiar with this lost chapter. For the first time, the text of “The Magic Envelope” has been translated into English so that fans of The Phantom of the Opera can read this forgotten gem. This chapter provides explanations for several enigmas that have puzzled readers since Leroux's first edition, and it offers a fascinating glimpse into the writing process of one of France's literary icons.