One summer night, Harry goes to the beach to find no one other than Draco Lucius Malfoy. Confused, Harry follows the boy and watches him, finding out what may be Draco's deepest, darkest secret.
Harry witnessed something dark involving Draco Malfoy and his father during the summer between events in GoF and Year 5. This is my personal favourite, I love this story no matter what others may think about it.