The Prisoner of Azkaban
¡°This is a useful little spell,¡± he told the class over his shoulder. ¡°Please watch closely.¡±
¡°Okay,¡± said Harry slowly, ¡°but why?¡±
Harry had the impression that Lupin wanted to leave as quickly as possible.
A shrill voice was laughing, the woman was screaming, and Harry knew no more.