In what is later revealed to be a dream/memory, a very young girl (Nan) walks with a man—the Sweep. The two are inseparable; they share food equally, sing together, and work together as chimney sweeps. After the Sweep and the girl finish cleaning a chimney, he soberly warns the house’s inhabitants to burn a hot fire that night to prevent birds from building a nest in the chimney. Then, the Sweep and the girl quietly climb up and sleep on the roof against the warm chimney.

Five young chimney sweeps, also known as “climbing children,” sleep in a coal bin: four boys and Nan, a girl. One of the boys, Newt, asks Nan to tell him about the Sweep; Newt dreamed of the Sweep the night before. People who sleep near Nan also tend to dream of the Sweep; specifically, they dream of the song that he and the girl with him used to sing. However, Nan refuses to admit that she is the girl in their dreams.

Roger, who has had the same dreams for the years he has slept near Nan, explains to Newt that the Sweep was Nan’s old master before Crudd (their current master), that he left Nan five years ago, and that Nan still hopes that he will return.