None of the performers on-screen are actors, just "faces" Dreyer found and cast. In fact, his "star" of the film is the fellow who financed it. And rather than being closeted in a film studio, Vampyr is shot on location in the natural world, made unnatural by the way Dreyer envisioned it and photographed it, with soft focus and a very mobile camera.
It is a horror film, but at a time when the recorded image was still new and growing. Fantasy, horror and science fiction had all made in-roads in cinema—George Melies had already made spectacular silent fantasy films on a stage environment in which he pushed in-camera effects and other photographic tricks in a controlled environment. Dreyer took those effects and threw them into the natural world, encroaching on the safety and security of the spaces we are used to and invading them with the other- and nether-worldly. It makes leaving the theater for the security of the real world a more uncertain thing.
It's certainly that way for Allan Gray (Nicholas de Gunzberg nee Julian West). He arrives at an inn near town and is awoken in the middle of the night by an old man (Maurice Schutz) who crept in and leaves him a package that says "Open in the event of my death." Picking up the parcel, Gray leaves the inn and encounters shadows that compel him to an ancient castle where the shadows cavort without the benefit of anything corporeal to create them, save for two elderly people he hasn't seen before. Creeped out, he leaves the castle and finds a nearby house where he sees the man who gave him the parcel, and is horrified to see him murdered before his eyes. Gray rushes to the door to be let in to help the stricken man and is let in by the house's servants. The man is dead, and Gray is compelled to stay the night. He meets Gisele (Rena Mandel), the man's daughter, who informs him that her sister Leone (Sybille Schmitz) is very ill and acting strangely.
Like walking outside the house in the middle of the night. Gisele and Gray follow her and find her unconscious, bite marks on her neck. They carry her back to the house and it is then that Gray opens his parcel—it is a book about vampyrs. Reading, Gray deduces that Leone is the victim of a vampire attack. The village doctor arrives to treat Leone and Gray remembers him as one of the old people he saw at the castle the previous night. Fearing that Leone is near death, Gray offers his own blood for a transfusion and the girl revives. But, when Gray wakes up later, he finds the doctor attempting to poison Leone. He pursues the doctor back to the castle and is beset by visions of himself being buried alive. Awaking from the dream, he conspires with one of the servants to pursue the doctor and hunt the vampyr to relieve the family of the curse hanging over the manor-house.
It may seem "old-hat" in these times of carnage by the gallon in cinema, but the aim of Vampyr was not to shock, but to impose on its audience a feeling of dread and distrust. Not only of the events of the story, but in the very way it is perceived—as if in real life. The camera slinks around rooms like someone pacing and scanning. Despite Rudolph Mate's glossy cinematography, a clear vision of things is frequently obstructed through fog, mist, distance and glass. We can never be "sure" in this world of Dreyer's. Is it real? Is it dream? Is it a little of both?
We can never be sure, and perhaps that dread is more horrible than anything born of curses and laboratories and cruelty. It makes our steady rock-solid world more precipitous and as sure as quick-sand.