In 1816, John William Polidori travelled to Geneva as Byron's personal physician; there he met Mary and Percy Shelley and took part in the most famous house party in literary history. To pass the time in 'a wet, ungenial summer,' the travellers took to writing ghost stories. Byron wrote his Faustian drama Manfred (1817); Mary Shelley wrote her masterpiece, Frankenstein; or The Modern Prometheus (1818). Polidori appropriated an unfished story by Byron and turned it into the The Vampyre (1819). Polidori's tale, with its nightmarish atmosphere and seductive, aristocratic villain, was a scandalous success; the fact that it was originally published, without Polidori's knowledge, under Byron's name, didn't hurt. All the most famous vampires of popular culture, from Stoker's Dracular to Anne Rice's Lestat, descend from Polidori's Byronic prototype. Polidori also contributed an original novel to the ghost-story project: Ernestus Berchtold, or, The Modern Oedipus (1819). Polidori's novel explores the incest theme common to such Romantic works as Manfred, Percy Shelley's Alastor, and M.G. Lewis's The Monk, and combines this Gothic material with a historical account of Napoleon's 1798 invasion of Switzerland, one of the key moments in the political evolution of Romanticism. This edition includes the extensive revisions Polidori made for a projected second edition of The Vampyre, Ernestus Berchtold is reprinted for the first time in the 174 years since its initial publication. The critical introductions and explanatory annotations place the two works in their biographical, historical, and literary contexts. Appendices include a new edition of the fragment by Byron on which The Vampyre was based, and a fragmentary tale by Polidori, never before published, which shows him exploring new literary direction after being fired by Byron and returning to England in disgrace.