"It might mean, literally, that the Door leads outside our world and universe," finished the inspector.
Ennis' haunted eyes stared. "You mean that this Door might somehow lead into another universe? But that's impossible!"
"Perhaps unlikely," Campbell said quietly, "but not impossible. Modern science has taught us that there are other universes than the one we live in, universes congruent and coincident with our own in space and time, yet separated from our own by the impassable barrier of totally different dimensions. It is not entirely impossible that a greater science than ours might find a way to pierce that barrier between our universe and one of those outside ones, that a Door should be opened from ours into one of those others in the infinite outside."
"A door into the infinite outside," repeated Ennis broodingly, looking past the inspector. Then he made a sudden movement of wild impatience, the dread leaping back strong in his eyes again.
"Oh, what good is all this talk about Doors and infinite universes doing in finding Ruth? I want to _do_ something! If you think this mysterious Brotherhood has taken her, you must surely have some idea of how we can get her back from them? You must know something more about them than you've told."
"I don't know anything more certainly, but I've certain suspicions that amount to convictions," Inspector Campbell said. "I've been working on this Brotherhood for many years, and block after block I've narrowed down to the place I think the order's local center, the London headquarters of the Brotherhood of the Door."
"Where is the place?" asked Ennis tensely.
"It is the waterfront café of one Chandra Dass, a Hindoo, down by East India Docks," said the detective officer. "I've been there in disguise more than once, watching the place. This Chandra Dass I've found to be immensely feared by everyone in the quarter, which strengthens my belief that he's one of the high officers of the Brotherhood. He's too exceptional a man to be really running such a place."
"Then if the Brotherhood took Ruth, she may be at that place now!" cried the young American, electrified.
Campbell nodded his bald head. "She may very likely be. Tonight I'm going there again in disguise, and have men ready to raid the place. If Chandra Dass has your wife there, we'll get her before he can get her away. Whatever way it turns out, we'll let you know at once."