"Adventure of the German Student" by Washington Irving tells the story about a young student called Gottfried Wolfgang who “wanders” into studies of speculation. As a result, he becomes secluded and his health—both physical and mental—declines. Wolfgang becomes preoccupied with the idea that an evil presence or spirit is hanging over him seeking to “ensnare” him. He is encouraged by friends and family to move from his home in Germany to Paris to recover from this fear and "melancholic temperament." His increasingly reclusive behavior has isolated him from his friends and family, putting him in his own dark world.

Paris initially proves his savior. He enjoys the philosophical discussion and the exciting atmosphere created by the French Revolution. Unfortunately, everything changes when the revolutionaries begin executing their enemies during the Reign of Terror. The public executions disgusted and shocked him, further contributing to his reclusive behavior. 

Alone in his student quarters, he begins to fantasize and dream about a woman "of a female face of transcendent beauty." He is haunted by this woman’s face over and over again, in his dreams at night and in his thoughts by day. The dream comes true when one night he walks through Place de Grève—where the executions take place—and walks by the guillotine. This guillotine had been used that very same day, and Wolfgang is understandably perturbed by it.  A storm is raging, too, with lightning flashes illuminating the scene. He sees the woman from his visions, dressed in all black, sitting on the steps of the scaffold of the guillotine.

Wolfgang is astonished to see her in real life. He notes that she seems of the higher class—perhaps she has been displaced as a member of aristocracy. He offers her a place to stay for the evening. In doing so, he appeals to her solitude by telling her that has no friends in the city, either, and would be happy to help another stranger in Paris. She agrees and accepts his offer of protection.

Wolfgang takes her home. In the light of the apartment, he gets a closer look at her. The only “ornamented” aspect of her otherwise simple attire is a black banded choker studded with diamonds. In a rush of emotion, he tells the woman of his visions. She seemed to be affected by his story. She even tells him that she felt a similar pull to him that evening. In this rush of feeling and conversation, Wolfgang pledges himself to her forever, and she agrees.

In the morning, however, Wolfgang leaves her sleeping in his bed. He sets off to find a more spacious apartment that the two of them can share. When he returns, he finds her dead and calls the police. Seeing her, the policeman is shocked; he says he had seen the same woman guillotined only the day before. He takes off her black collar and the woman's head rolls onto the floor.

Wolfgang is horrified, especially due to his fear that an evil spirit will enthrall and overtake him. According to the narration, he was committed to an institution and died in a mental asylum.

The story finishes by introducing the story's narrator, who is telling his friend that the story is, in fact, true; he claims that he saw Wolfgang in the mental asylum in Paris and heard the tale from Wolfgang himself.