Gottlieb Biedermann, a businessman, while on his way home, lights a cigar and witnesses the Chorus of Firemen setting their watch. Afterward, at home, seated in his living room, reading the newspaper, Biedermann vents his disgust with the arsonists plaguing his city, convinced that they should all be hanged. He is interrupted by Anna, his servant, who informs him that a peddler waits to see him. Biedermann tells her to get rid of the man, but the intruder enters unbidden, identifying himself as Sepp Schmitz, a circus wrestler. The astonished Biedermann, nonplussed by the stranger’s sudden appearance, invites the ingratiating Schmitz to have some bread, which the visitor manages to parlay into a substantial snack through flattery and self-deprecation mixed with quiet but insistent demands. Their discussion is briefly interrupted when Herr Knechtling, a former employee released by Biedermann, comes to the door seeking an audience. His request outrages Biedermann, who directs Anna to send him away. He then takes Sepp to his attic, where the visitor is invited to stay on the condition that he swears that he is not an arsonist—one of the firebugs. Sepp only laughs, but Biedermann, satisfied, permits Schmitz to stay.

The next morning, after Biedermann’s wife, Babette, spends a troubled night, fearful that there might be a firebug in the attic, Biedermann introduces her to Schmitz before leaving for work. Although Babette is determined to send the wrestler away, she feeds him breakfast while searching for a tactful way of doing so. Sepp plays on her kindness, preparing her to receive the next suspicious guest, Willi Eisenring, an unemployed waiter. The next day, Biedermann, set on throwing both men out, goes to his attic, where Schmitz and Eisenring just finish stacking up some large drums. Biedermann’s anger is soothed by Willi, who admonishes Sepp for his lack of manners and insensitivity to Biedermann’s feelings. Biedermann spots the drums and becomes alarmed. The labels clearly reveal their contents: gasoline. He then threatens to call the police, but a policeman already arrives to tell Biedermann that Herr Knechtling committed suicide the previous night. Oddly, when the policeman asks what is in the drums, Biedermann tells him it is only Hormotone, the hair tonic made by Biedermann’s firm. After justifying his behavior to the Chorus of Firemen, arguing that one has to maintain trust in people, Biedermann explains to Babette that even if the two men are firebugs, it is best to treat them as friends. He then tells her to include them for dinner.

Somewhat later, in the attic, Eisenring explains to the increasingly officious Biedermann that Sepp is out on an errand, looking for sawdust to help spread the fire. He also explains that he is a former prisoner and tells Biedermann that he is looking for a detonator cap. Biedermann takes these bald admissions as a joke, and Eisenring confirms that a joke is a good camouflage but that the truth is even better. He then tactfully advises Biedermann to extinguish his cigar and asks him to help wire the detonator and fuse. Unshaken, Biedermann reveals that he comes to invite Eisenring and Schmitz to dinner. After Biedermann leaves, Eisenring tells the professor, a Ph.D., to come out from the pile of gasoline drums, to keep guard while he and Sepp go to the dinner. The professor tries to warn Babette about the arsonists, but Babette, who accepts Biedermann’s idea that they should not offend Eisenring and Schmitz, does nothing.

Before the dinner, Biedermann directs Anna to remove the table finery she puts out. Then, after a funerary wreath is delivered that mistakenly identifies...