re was a blank wall
with one door and a pair of gates. The girl took a key from her bag,
opened the small door and stepped in, and Beale followed.

They were in a yard littered with casks. On two sides of the yard ran
low-roofed buildings which had apparently been used as stables. She
locked the door behind her, walked across the yard to the corner and
opened another door.

"There are fourteen steps down," she said, "have you a light of any
kind?"

He took his electric torch from his pocket.

"Give it to me," she said, "I will lead the way."

"What is this place?" he asked, after she had locked the door.

"It used to be a wine merchant's," she said shortly, "we have the
cellars."

"We?" he repeated.

She made no reply. At the bottom of the steps was a short passage and
another door which was opened, and apparently the same key fitted them
all, or else as Beale suspected she carried a pass key.

They walked through, and again she closed the door behind them.

"Another?" he said, as her light flashed upon a steel door a dozen paces
ahead.

"It is the last one," she said, and went on.

Suddenly the light was extinguished.

"Your lamp's gone wrong," he heard her say, "but I can find the lock."

He heard a click, but did not see the door open and did not realize
what had happened until he heard a click again. The light was suddenly
flashed on him, level with his eyes.

"You can't see me," said a mocking voice, "I'm looking at you through
the little spy-hole. Did you see the spy-hole, clever Mr. Beale? And I
am on the other side of the door." He heard her laugh. "Are you going to
arrest the doctor to-night?" she mocked. "Are you going to discover the
secret of the Green Rust--ah! That is what you want, isn't it?"

"My dear little friend," said Beale smoothly, "you will be very sensible
and open that door. You don't suppose that I came here alone. I was
shadowed all the way."

"You lie," she said coolly, "why did I dismiss the cab and make you
walk? Oh, clever Mr. Beale!"

He chuckled, though he was in no chuckling mood.

"What a sense of humour!" he said admiringly, "now just listen to me!"

He made one stride to the door, his revolver had flicked out of his
hip-pocket, when he heard the snap of a shutter, and the barrel that he
thrust between the bars met steel. Then came the grind of bolts and he
pocketed his gun.

"So that's that," he said.

Then he walked back to the other door, struck a match