Heard any good vampires lately? Now's your chance. Wolf Trap has finally decided how and where it wants to present "Der Vampyr" by Heinrich Marschner. Originally announced for the big shed, the ghastly ghostly is now scheduled for the handsome auditorium of the Madeira School where it will be given two performances this week: 8 p.m. on Thursday and midnight on Saturday.

The source of Marschner's opera arose in June of 1816, at the famous villa called Deodati on the shores of Lake Geneva, in what Mary Shelley, the wife-to-be of Percy Bysshe Shelley, and the author of "Frankenstein," later described as "that wet, ungenial summer." Of course, reports of vampires had been circulating for centuries, and things had gotten to the point where, in 1732 (the same year in which Josef Haydn and George Washington were born), Emperor Charles VI of Austria had prepared and published an official report on the subject. In 1755, the Empress Maria Theresa was so shocked by a later account of current vampire operations that she took strong steps "to combat the spread of so-called vampires and magic."

In that summer of 1816, gathered in the Villa Deodati were: George Gordon, Lord Byron; Mary Godwin (later Shelley); her stepsister Claire Clairmont (who had chased Byron across part of Europe to be near him when she bore his child); and Byron's physician, Dr. John Polidori. It was this last character who wrote the famous story, "The Vampire," on which, only a little over a decade later, young Marschner would write his first important opera.

It was a cozy crowd. Shelley was taking laudanum for his headaches. Byron was onto something called Black Drop, a popular tranquilizer of the time. And other vacationers around the lake were watching the villa (where they said there were orgies of group sex) through field glasses. In the villa, they sat around telling nasty bedtime stories. It would be a close call to say whose story had the most lasting effect, but Mary Shelley's "Frankenstein" and Polidori's "Vampire" must have shared the honors. (It was not until 1896 that Bram Stoker came up with his famous vampire novel, "Dracula," further to immortalize that summer gathering.)

In Polidori's story, Lord Ruthven is the villain, a demonic figure said to be modeled on Byron. When "The Vampire" first came out, everyone insisted that Byron had written it, an assertion that infuriated the great poet to such an extent that he quickly published his own "Fragment," a much less diabolical wisp of a story from which nearly all suggestions of vampirism had been removed. In polidori, Lord Ruthven's true nature was only revealed to his close friend, Aubrey, late in the narrative. At the end of the tale, "The guardians hastened to protect Miss Aubrey [the sister of the hero], but when they arrived, it was too late. Lord Ruthven had disappeared, and Aubrey's sister had glutted the thirst of a vampyre!"

In Marschner's opera, there is a different ending: His vampire disguise is exposed and he is killed by lightning.

Marschner was a contemporary of Weber, from whom his music took great inspiration. When Weber died in 1826, Marschner succeeded him as Kappelmeister of the opera in Leipzig. Weber, always a generous man toward his colleagues, had already produced two of Marschner's earlier operas in Dresden. And Richard Wagner, during his brief stint as music director in the same city in 1845, conducted Marschner's "Kaiser Adolf von Nassau." The Marschner influence remained extremely strong. It was from his opera on the subject of "Ivanhoe," that Schumann took the theme for his well-known Etudes Symphoniques.

Throughout the 66 years of his life, Marschner's favorite subjects where ghosts and demons and their revels. This accounts for a great part of the success of "Der Vampyr," which ran for 60 nights in London when it was given there one year after its world premiere in Leipzig. This was Marschner's first important opera, surpassed in popularity, in Germany at least, by what is probably his finest work, "Hans Heiling." More than a century later, it is regularly produced in German opera theaters.

The libretto for "The Vampyr," was written by Marschner's brother-in-law, Wilhelm August Wolhbruck. It is the kind of libretto, on the kind of subject, that seems likely to inspire Sarah Caldwell to special heights of quintessential romanticism, mixed as it is with the macabre and the fantastic. It was in order to give Caldwell the freest rein possible that the production was moved from the big Wolf Trap shed stage to the more intimate confines of the Maderia School auditorium. In that excellent theater, Caldwell is planning the special effects and highly plausible/implausible visions that should surround any proper vampire. Cast from the Wolf Trap Company and to be conducted by Fred Company of Boston, these showings of "Der Vampyr" may even succeed in shilling the blood on the hottest of summer evenings -- 164 years after the first wet, ungenial summer night.