The Butler, A Spectator (その執事、歓望, Sono Shitsuji, Kanbō) is Chapter 31 of the Kuroshitsuji manga.
Joker has prepared dinner for them, which Sebastian tests for poison. Baron Kelvin arrives with brainwashed children in tow, excited by Ciel's presence. While eating dinner, Baron asks Joker to prepare a performance for him, which he is noticeably hesitant about doing. Nonetheless, upon Baron’s insistence, he prepares the act.
First, a tightrope walker and then an animal trainer are killed gruesomely during the performance, as it is clear they are untrained children. Joker and Ciel are clearly upset by their deaths, while Baron finds it humorous, applauding and laughing. As a dagger thrower nearly hits a child, Ciel orders Sebastian to stop the performance, which he does. Baron, surprised by Ciel's disgust, orders Joker to clean up the act.
Ciel calls Baron vulgar, ugly, and perverted, stating he has no desire to remain at the same table as him. As he pulls out a gun on Baron, Joker dashes forward with a sword on Ciel, while Sebastian pulls a knife on Joker. Baron orders Joker to "stop pointing that dangerous thing" at Ciel, who then asks where the rest of the kidnapped children are. Baron agrees to lead him to his basement, where he has another surprise for Ciel.
It turns out that Baron has created a replica of the room Ciel was sacrificed in, and asks for a reenactment. He recalls meeting Ciel five years ago, and the beginning of his obsession with him.