London
Nights at the Circus begins with American journalist Jack Walser interviewing Sophie Fevvers in her London dressing room, following her performance in the circus which employs her. Fevvers claims to have been left as a baby in a basket on the doorstep of a brothel. Until she reached puberty she appeared to be an ordinary child, with the exception of a raised lump on each shoulder; as she begins menstruating, however, she also sprouted complete wings. As a child, she posed as a living statue of Cupid in the reception room of the brothel, but as an adolescent, she is now transformed into the image of the "Winged Victory" holding a sword belonging to Ma Nelson, the madam of the brothel. This stage of Fevvers' life comes to an abrupt end when Ma Nelson slips in the street and falls into the path of a carriage. The house and its contents are inherited by her pious brother who plans to convert it to a house for fallen women, but Ma Nelson's employees burn the place down and go their separate ways.
Fevvers continues her story, although doubt is cast on the veracity of her narrative voice throughout. She and Lizzie, she tells Walser, next move in with Lizzie's sister and help run the family ice cream parlour. However, when the family falls on hard times Fevvers accepts an invitation from the fearsome Madame Schreck. She puts Fevvers on display in her exclusive combination of freak show and brothel, along with several other women with unique appearances. After some time, Madame Schreck sells Fevvers to a customer, "Christian Rosencreutz", who wishes to sacrifice a winged 'virgo intacta' in order to procure his own immortality. Fevvers narrowly escapes and returns to Lizzie's sister's home. Soon after their reunion, she joins Colonel Kearney's circus as an aerialiste and achieves enormous fame. The London section concludes with Walser telling his chief at the London office that he is going to follow Fevvers, joining the circus on its grand imperial tour.
Petersburg
The Petersburg section begins as Walser, living in Clown Alley, types up his first impressions of the city. The reader learns that Walser approached Colonel Kearney who, taking advice from his fortune telling pig Sybil, offered him a position as a clown in the circus. The reader, and Walser, are introduced to the other members of the circus and Walser saves Mignon from being eaten by a tigress.
In the next scene the chief clown Buffo and his troupe invoke chaos at their dinner table. Walser ducks out of the meleé only to find Mignon waiting outside for him, as she has nowhere else to go after her husband and lover have both abandoned her. Not sure what to do with the abandoned woman, he takes her to Fevvers's hotel room. Fevvers assumes that Walser is sleeping with Mignon but, though jealous, takes care of the girl. On recognising the beauty of Mignon's singing voice Fevvers introduces her to the Princess of Abyssinia. The Princess, a silent tiger tamer, incorporates Mignon into her act with the dancing cats and Walser is recruited as partner to the redundant tigress. During rehearsals, the acrobatic Charivari family tries to kill Fevvers and the Colonel reluctantly kicks them out of the circus. Buffo the Great loses his mind during that night's performance and tries to kill Walser. The Princess has to shoot one of her tigresses when she becomes jealous of Mignon for dancing with her tiger mate during the tiger waltz. After her performance, Fevvers goes to a date at a mansion belonging to the Grand Duke. Here, she almost falls victim to his amorous advances but narrowly escapes into a Fabergé egg, reaching the circus train as it is about to pull out of the station. This last scene is deliberately bewildering, developing the sense of doubt cast upon the reader in Fevvers' early narrative and laying the foundations for the fantastic occurrences of the final section..
Siberia
The Siberian section opens with the entire circus crossing the continent to Asia. The train is attacked by a band of runaway outlaws who think that Fevvers can help them make contact with the Tsar, who will then allow them to return home to their villages. As the train is now destroyed, the entire circus, other than Walser, is marched to the convicts' encampment; Walser is rescued by a group of escaped murderesses and their former guards, who have become their lovers and helped them to escape. As Walser has amnesia, the band of women leaves him for an approaching rescue party but he flees into the woods before they reach him and is taken under the wing of a village shaman.
Fevvers and the rest of the party are being held captive by the convicts. Fevvers tells the convict leader that she cannot help them as everything that they have heard about her is a lie. Depressed, the convicts sink into drunken mourning. Lizzie convinces the clowns to put on a show for the convicts, during which a blizzard comes, blowing the clowns and the convicts away with it into the night. The remnants of the circus begin to walk in the direction in which they hope civilization lies. They come across a run-down music school and take shelter with its owner, the Maestro. A brief encounter with Walser, now thoroughly part of the shaman's village, convinces Fevvers and Lizzie to leave the safety of the Maestro's school to search for Walser. Colonel Kearney leaves the group to continue his quest for civilization so as to build another, and more successful, circus. Mignon, the Princess and Samson remain with the Maestro at his music school. Fevvers finds Walser and the story ends with them together at the moment that the new century dawns and Fevvers' victorious cry "to think I really fooled you".
