Dumbledore spent a while longer probing along the cavern walls with his wand. Finally, he paused at one spot, then pretended he had found nothing and told the others:
"This is only the antechamber, the entrance hall. We need to find the entrance here... clearly, this is no natural obstacle. Tom has set up a mechanism to stop us... so see if you can find that mechanism and open it."
Sirius gave a wry smile. "Albus, we've already graduated... we should hurry..."
Dumbledore interrupted Sirius, saying gravely, "This is a rare opportunity to understand Tom's magic and pit ourselves against him... Douglas is right. We should make good use of this opportunity..."
As he spoke, Dumbledore even winked at Douglas.
Douglas looked utterly bewildered. What are you winking at me for? When did I say they should seize this opportunity?
Seeing Sirius and Lupin looking his way, Douglas nodded solemnly.
Then Douglas watched Sirius and Lupin exchange a glance, step apart, and gesture for him to proceed. Lupin said with a smile:
"I think we ought to let a young man who's never witnessed Voldemort's abilities have this opportunity first... what do you think, Padfoot?"
Sirius looked at Douglas. "I can't help agreeing with such an excellent idea."
The corner of Douglas's mouth twitched. He looked at Dumbledore, who gazed up at the cavern ceiling as though some vortex there had caught his attention.
Douglas raised an eyebrow and took the Magic Radar out of his pocket. Who do you think you're underestimating?
He adjusted the Magic Radar, then inserted its probe into a crack in the rock. Soon, a structural diagram of the entire cavern appeared on the display.
Sirius and Lupin did not understand what this meant, but Dumbledore studied the displayed information with interest. He was not