howed a hint of hooded horror,
yet he shook his head. "I know no more than you. But whatever they do to
the victims, they are never heard of again."

"But you must know something more!" Ennis protested. "What is this
Door?"

Campbell again shook his head. "That too I don't know, but whatever it
is, the Door is utterly sacred to the members of the Brotherhood, and
whomever they mean by They Beyond the Door, they dread and venerate to
the utmost."

"Where leads the Door? _It leads outside our world_," repeated Ennis.
"What can that mean?"

"It might have a symbolic meaning, referring to some secluded fastness
of the order which is away from the rest of the world," the inspector
said. "Or it might----"

He stopped. "Or it might what?" pressed Ennis, his pale face thrust
forward.

"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 caf