Harry's sixth year at Hogwarts. The death of Sirius Black made him incredibly determined to destroy Voldemort, his followers, and Death Eaters. Dumbledore picks him up from the Dursley's, and then Harry helps Dumbledore convince his new Proffeser Slughorn to be a Proffeser again, and he said yes.
When Harry arives at Hogwarts, he is Quidditch captain, and Snape got the position he really wanted: Defence Against the Dark Arts. Proffeser Slughorn was the potions proffeser. A mysterious owner of his potions book before, called the Half Blood Prince, wrote in the book tips and changes to make the potions better. they allworked better than what the book said.
Harry suspects malfoy is a death eater, or at least his family is, and Harry is trying to bust him. Harry and Dumbledore are working on destroying a Horcrux,somthing that contains 1/8 of VoldemortsSoul. Bad things happenincluding dying and voldemort, and now its the 7th year at Hogwarts.