"The entrance to Classroom 21 is related to Gamp's Law of Elemental Transfiguration." Albert led Katrina to a corridor on the sixth floor of the Castle.
"What is this, some kind of test?" Katrina arched an eyebrow, looking at the portraits along both sides of the corridor. She knew that hidden passageways were often concealed behind portraits and tapestries.
Albert smiled and said, "If you want to look at it that way, I won't deny it."
Chapter 111