Ciel Phantomhive and Sebastian Michaelis prepare to head to London. Ciel tells Baldroy, Finnian, and Mey-Rin to look after the Phantomhive Manor while he is gone. During the carriage ride, Ciel reads a letter written by Queen Victoria; she informs him of children going missing wherever the Noah's Ark Circus visits, and urges Ciel to investigate.
At the file room of the Scotland Yard headquarters, Ciel remarks that it is convenient Arthur Randall is absent. Fred Abberline attempts to persuade them to cease their unauthorized search, but they do not heed to him. Sebastian gathers data verifying that no bodies have been found that match the report of the missing persons. Ciel tells him to copy the documents and borrow the photos and assures Fred that he can just say it is Ciel's fault if he gets found out. Ciel shows his thanks for Fred's cooperation by having Sebastian grant him money. Fred refuses the payment, declaring that he is merely doing whatever it takes to bring the children home, and Ciel admires him for his flexibility.
Ciel and Sebastian, then, go to Undertaker's funeral parlor. They give Undertaker the details of the children and ask if any of them has been handled by him. Undertaker, however, demands "prime laughter" before he is to present the required information. After Undertaker mocks Ciel for constantly relying on his butler, Ciel sends Sebastian away and endeavors to make Undertaker laugh by himself. He eventually succeeds, and Undertaker divulges that none of the children was his customer. Sebastian deduces that that means no one in the underworld society has killed them. Ciel, then, concludes that since the children are still alive, their only choice is to personally investigate the Noah's Ark Circus. Before Ciel and Sebastian leave, Undertaker warns Ciel to take good care of his soul.
Subsequently, Ciel and Sebastian attend a Noah's Ark Circus show. Joker welcomes the audience and performs risible tricks. Jumbo starts the show by breathing fire. Peter and Wendy, both trapeze artists, conduct stunts. Dagger demonstrates his precise knife-throwing skills. Snake executes a unique dance with his snakes. Doll carries out a "death-defying" tightrope walk. Ciel and Sebastian notice that the Circus does not seem to be forcing children to take part in the act, and Ciel wonders if the missing children along the Circus's route is simply a coincidence. Beast, the "star" of the troupe, then tames a tiger. Joker asks for audience participation in their final act, and Sebastian goes on stage. Ciel thinks Sebastian is volunteering in order to investigate the Circus. However, Sebastian ignores Joker's instructions and walks directly to the tiger to caress and compliment it. Ciel realizes, to his dread, that tigers are cats. Joker, Beast, and the audience are astonished by Sebastian's bizarre behavior. The tiger, then, bites Sebastian's head, much to the horror of the audience. Beast orders the tiger, Betty, to let Sebastian go by whipping it, but Sebastian catches the whip, saying that Betty did not do anything wrong, and reproachfully asserts that indiscriminate whipping is not proper training, to Beast's chagrin. Betty bites Sebastian again, thus inciting another uproar.
Outside, Ciel scolds Sebastian for attracting unnecessary attention and commands him to stay far back from him for he is allergic to cats. Suddenly, Joker calls Sebastian and apologizes. He requests for Sebastian to come with him and get examined by their doctor, and Ciel discreetly gives his nod of approval.
Soon after, Doctor, who was helping Dagger with his leg, inspects Sebastian and says that he has no wounds. Joker reveals that he is the surrogate leader and not the actual one. Beast, then, enters the tent to get her leg checked. Dagger is delighted by the sight of her, but Beast ignores him and confronts Sebastian. Doctor censures her for yelling at Sebastian, a guest, and then assesses her prosthetic leg. Joker explains to Sebastian that they are a "gathering place" for people with certain problems. He states that he is missing an arm himself, but Doctor has replaced it with a prosthesis. Doctor affirms that he constructs the prostheses, from the carving to the final fitting, and proclaims that the prostheses are ceramic.
Sebastian scrutinizes Beast's leg while commenting on its smoothness; he ends up lifting it, much to Beast's mortification and Joker's and Dagger's surprise, and finds a seal. Beast lashes out at him, and Sebastian retorts that Beast did not strike him as "modest enough to be embarrassed by such trifles." She attacks him with her whip, and he easily dodges each blow. Doctor tries to get Joker and Dagger to intervene, but Dagger erupts out of anger that Sebastian has touched Beast's skin, and throws knives at him, though Sebastian fluidly evades the attacks. Sebastian points out that he did not actually touch her skin, but admits that he may have touched a nerve. Doctor seeks to convince Dagger to desist from fighting as it may destroy the tent, but Dagger argues that Beast's honor is more important than the tent. He tosses more knives at Sebastian, but the latter catches each and every one of them. Dagger is shocked, while Joker is impressed. Beast makes an effort to whip him again, but Joker suppresses her assault with his staff. He presents her with flowers to calm her down, and Doctor admonishes Joker for not stopping them earlier.
Joker, then, expresses his respect for Sebastian's athletic talent and says that he would hire Sebastian. Sebastian urges him to do so, as he is "quite disgusted" with his spoiled master, and Joker is astounded to learn that he is a servant rather than a person of the gentry. Sebastian assures him that he never jests, and presses Joker to hire him. Joker, amused, allows him to join them, despite Beast's disagreement. Sebastian, then, announces that there is another person he would like to introduce to them. Joker informs him that the said person will be given an entry test, and Sebastian states that he will return with the person tomorrow for the exam.
Sebastian, then, departs from the tent. He muses that there were nine tents and ten carts before the medical tent; further along, are more elegant tents. He also notes that there are no children around at all, but acknowledges that he is sensing something. Before he can continue exploring, however, Snake stops him, saying that the area Sebastian is about to trespass is off-limits.