They were going even deeper now and gathering speed. The air became colder and colder as they hurtled round tight corners. They went rattling over an underground ravine, and Harry leaned over the side to try to see what was down at the dark bottom, but Hagrid groaned and pulled him back by the scruff of his neck.

Vault seven hundred and thirteen had no keyhole.

“Stand back,” said Griphook importantly. He stroked the door gently with one of his long fingers and it simply melted away.

“If anyone but a Gringotts goblin tried that, they'd be sucked through the door and trapped in there,” said Griphook.

“How often do you check to see if anyone's inside?” Harry asked.

“About once every ten years,” said Griphook with a rather nasty grin.

Something really extraordinary had to be inside this top security vault, Harry was sure, and he leaned forward eagerly, expecting to see fabulous jewels at the very least — but at first he thought it was empty. Then he noticed a grubby little package wrapped up in brown paper lying on the floor. Hagrid picked it up and tucked it deep inside his coat. Harry longed to know what it was, but knew better than to ask.

“Come on, back in this infernal cart, and don't talk to me on the way back, it's best if I keep me mouth shut,” said Hagrid.