Taken from Harry Potter and The Prisoner of Azkaban, the third novel in the Harry Potter series written by renown author JK Rowling. This image was created by Mary Grandpré, who illustrates the covers for the Harry Potter books.
In this image, unbeknownst to all but Ron, Harry hides beneath the cloak of invisibility in order to leave Hogwarts grounds without permission. While Malfoy, Crabbe and Goyle taunt Ron outside the Shrieking Shack, Harry throws mud at the loathsome trio. Yet, his invisibility cloak is caught by Goyle as the three scramble about, causing Harry's head to appear and seemingly float in midair, which when sighted, completely unnerves Malfoy and his two followers.