Full summary for '4':

It’s back to Hogwarts as the trio vow to finish their NEWTs, in a year that threatens to be their darkest yet. Haunted by visions of the dead and the pull of the Resurrection Stone, Harry must fight a terrible curse as he works to uncover an ancient secret. What is '4'? How has it appeared so frequently in history? And why is everybody around him so keen to conceal it? (Harry/Draco slash.)