The Butler, Presenting is Chapter 135 of the Kuroshitsuji manga.
Ciel wakes up in a suitcase. He is bound and gagged and transported in a carriage. For a moment, Ciel is irritated by his situation before he remembers what happened at Phantomhive Manor, and starts to cry.
Eventually, the carriage stops, and Ciel is unloaded. Two men take him out of the suitcase and pierce a price tag on his left ear. When they are done, another man brings "Ciel", who was already tagged, as the twins have to be sold together, or "their value'll drop," hence they are put into the same cage.
Ciel is glad that his brother is alive, but "Ciel" does not respond to his twin's words. Instead, he says that he failed as the Phantomhive family's eldest son and heir, and wishes he had more power. Seeing his brother saying these things and crying makes Ciel realize that they were not so different after all, and that they were "equally powerless." Then, the twins embrace each other and cry together.
At night, "Ciel" wakes up Ciel to show him the blue Phantomhive family ring. "Ciel" says that, as the ring can only be worn by the head of the Phantomhive Household, he took it from their father's finger when he discovered his corpse. Then, "Ciel" adds that the ring will guide their way back to the manor, and when they have returned, they would be able to start anew.
To make sure that nobody can take the ring away from them, "Ciel" swallows it, and Ciel has to promise not to tell anyone "Ciel" "swallowed that blue candy." They make a prayer, and the next day, a man comes to see the twins.
The man is delighted to notice that they are not only twins, but the Phantomhive twins. However, he does not inform the human trafficker about this, in order not to have to pay more. The man buys the twins and brings them to his mansion where they are washed and dressed and given something to eat. In the evening, Ciel and "Ciel" are dressed up and taken to a seemingly abandoned cathedral faraway.
The twins are guided inside where numerous people in heavily modified monk's or nun's robes and feather masks are gathered, and the man who bought them tells them that "there's nothing to be scared of" while putting on his robes and mask.
Afterward, another man talks about the new moon and how "The powers of [the] wicked king reach their peak," and they have to "defile [the twins'] pure souls," for the devil they are worshipping. Then, the twins are assaulted and molested by the members of the cult.
In the end, Ciel lies on the cathedral's ground and sees the statue of an angel, wondering why God is smiling.