Lucius failed at the Ministry, and Draco is sent to Hogwarts with a cryptic warning that he will be tasked with an unknown mission. He expects to spend his sixth year on prefect rounds with Pansy and finally beating Potter on the Quidditch Pitch. He never expected his new roommate to be Voldemort himself, or that Voldemort's obsession with trophies would apply to him.
The war is over and the castle rebuilt, and Hermione returns to Hogwarts in hopes of their first normal year. But Hogwarts unveils a new plan for unity, mixing all students into a new house. Any hopes for a quiet year are dashed when Hermione is left to share a dorm with Draco Malfoy.