Draco drinks a potion that makes him know if a person is lying, and Harry, apparently at fault that Draco is this way, is forced to 'help' him with the effects of the potion. For the first time, they deal with each other with no lies to hide behind.

Harry and Draco are both starting as Hogwarts professors at the same time. Their students quickly start to get a slightly different impression about their relationship than Harry and Draco have.