Harry Casts a Patronus to Fend Off Fake Dementors
Pages 261-263
Harry sees what he believes are three dementors near the Quidditch pitch and immediately casts a Patronus to protect himself. To his surprise, the dementors are revealed to be Draco Malfoy, Crabbe, Goyle, and Marcus Flint, dressed in black robes, trying to sabotage Gryffindor. Professor McGonagall punishes them with detention and deducts fifty points from Slytherin.