Harry Potter and the Hall of Echoes

After a chance meeting with Ron and Hermione in Diagon Alley, Harry finds himself packing his bag for another adventure. He has received an invitation to a mysterious wizards’ school, where they like to combine magic with Muggle inventions. What’s in that strange, wooden box? Who is the House Elf with peculiar powers? And what lies behind the door in the Hall of Echoes?