Harry gets a surprise visit from the trouble making elf Dobby, who warns Harry against returning to Hogwarts where terrible things will happen. Harry decides to ignore Dobby's warning and returns for his second year at wizarding school. So after his arrival strange and unexplained things start to happen, just as Dobby predicted. Harry is suddenly hearing mysterious voices from inside the walls, muggle-born students are being attacked, and a message scrawled on the wall in blood puts everyone on edge.