Vampyr doesn't have a plot, at least not one it sticks with. The film claims to be inspired by Sheridan Le Fanu's ghost story collection In a Glass Darkly, and in particular, the vampire theme appears to take some substance from its most famous story Carmilla. It is however no literal adaptation, but an inspiration of mood and atmosphere.
Before we discuss Vampyr itself, a word about Carl Dreyer. Known more for brooding dramas like Day of Wrath and Passion of Joan of Arc (which I have seen and can attest to), Dreyer was a highly individualistic director, whose short filmography (a consequence of his failure as a box-office draw) has served as immense inspiration to film-makers several generations over. Interestingly enough, Vampyr was originally intended as a more "commercial" venture, one that would give him acceptability after Passion...'s losses. Unfortunately for Dreyer, his vision for Vampyr was at odds with the expectations of audiences and did little to mitigate his increasing detachment from the mainstream movie world; his subsequent films came out with approximately a decade's gap between each.
To be fair, one sympathizes with those audiences. Vampyr, whatever its innate qualities, is in no way an accessible film. Quite the opposite, it almost requires that you be a horror connoisseur with a willingness to immerse in its slowly but relentlessly building creepy sepulchral atmosphere.
Vampyr may be divided into 3 main acts:
We are introduced to protagonist Allan Gray (Julian West aka Baron Nicolas de Gunzburg, a Russian nobleman who also financed the film). A large chunk of text tells us that he is a dreamer and student of occult knowledge whose distinction of the real and unreal realms is blurred (Yes, text. Technically, Vampyr HAS sound, but Dreyer intended it to be more in the vein of a silent film. Dialog is at an absolute minimum and most information is conveyed as inter-titles or as books the characters are perusing.). In the course of his wandering Gray finds himself in a river-side town one evening and checks himself into an inn (all without a word). At night, waking from a dream, (or does he, because the film's central conceit is that almost everything is seen through Gray's POV and may only represent his own flawed perception), Gray sees his room door open and a mysterious old man enters. Entreating him with the words "She must not die!" the old man leaves a package ("to be opened after my death") and leaves.
Gray hurries out to the village in deep night (presumably to follow the old man) and walks into a phantasmagoria: In an undoubtedly intense collaboration with his cinematographer Rudolph Maté, Dreyer shows us shadows that appear to move independent of bodies, performing such bizarre actions as un-digging a grave. Going in loose pursuit of these body-less silhouettes, in particular a guard with a peg leg, Gray runs into the village doctor, who shares the mysterious, malevolent mood of the night. Sometime after this and more eerie events, Gray goes towards a stately but decadent mansion where he sees the old man who appeared in his room...only for the old man to get immediately shot by a shadow. This could again be an act of Gray's imagination and the old man could have died of natural causes, since no one in the house is concerned about informing the police.
The bulk of the film's vampire element resides here. The old man is survived by two daughters, one of whom, Leone, is bed-ridden with severe loss of blood. This is revealed to be the handiwork of an aged vampire, Marguerite Chopin, who in some unspecified way, also controls the body-less shadows (Could it be she first sucks away the will of her victims by way of the shadow? Initially we see the peg leg guard's shadow doing her bidding, and then the man himself is shown to be her servant). Gray makes himself comfortable in the household (no questions asked about who he is and how he came to drop by without notice) and in his passive manner courts the other daughter, Gisele. More so than the other characters in Vampyr, Gisele and Gray are depicted in the manner of archetype silent film players; with her melancholic face and large eyes highlighted with mascara, Gisele could have walked right out of The Cabinet of Dr. Caligari.
Here again, Gray opens the package left by the old man and finds a handy tome of vampire lore which in his reading he shares with the audience - Hardened horror buffs might balk at this info-dump but should remember here that prior to Vampyr there were few known films on the theme, apart from Murnau's Nosferatu (1922) and Tod Browning's Dracula (1931). Meanwhile Leone, under the care of the mysterious doctor (who persuades Gray to give her blood, one of the few actively heroic acts Gray will perform), is beginning to display half-formed vampiric tendencies; her lip-smacking glances towards the nun tending her bring to mind Bram Stoker's description of Dracula's female vampires, "there was a deliberate voluptuousness which was both thrilling and repulsive, and as she arched her neck she actually licked her lips like an animal, till I could see in the moonlight the moisture shining on the scarlet lips and on the red tongue as it lapped the white sharp teeth". After a premonitory dream, Gray saves Leone from the malevolent doctor's plan to make her commit suicide (thereby forever losing her soul), and goes after him. In the meanwhile the old servant of the household resumes the reading of the vampire tome (right from where Gray left off) and figures out the means of destroying Marguerite Chopin's evil.
The last act of Vampyr follows Gray as he goes out after the doctor. Unable to track him, he sits exhausted on a bench. A translucent “spirit” version of Gray then stands up, leaving the body on the bench and goes wandering until he comes upon the doctor's lair where he sees a coffin and on opening it....finds his own corpse. So at this point in the film you have 3 Grays: One on the bench, the spirit avatar and the corpse in the coffin. The plot has no accounting whatsoever and there seems little reason for this other than for Dreyer to capture some visually interesting scenes. In that, he is quite successful, especially the bravura moving shot in which we see the coffin being carried around from the point of view of the Gray lying (apparently alive, but in cataleptic state) in it. Besides its visual audacity it is the ultimate crystallization of the film's theme of ever-impending death.
Shortly after, we have the abrupt push to wrap up the film's proceedings. Marguerite Chopin's grave is broken into and her corpse given the customary stake treatment (here's it's an iron stake to connect the vampire's body to the earth), Leone is freed from her descent into the vampiric and the evil doctor is given his comeuppance by a gruesome (for the time) suffocation when he buried in the product of the flour mill. There's also an appearance by the old man's ghost; he takes revenge on the peg leg guard whose shadow shot him.
Those looking for a nicely bookended narrative will no doubt be frustrated, but it may be said the inconsistencies and convolutions of Vampyr's plot, coupled with its foggy languorous visual style and sparse but carefully constructed soundscape serve to heighten the strange dream-like mood Dreyer wishes to project onto the audience. While not easily recommended to all (and I certainly won't hold it against you for being put off by it), Vampyr has its own delights for the genuine connoisseur of the horror film.