But the bed, all clean and white, had not been disturbed.

Simultaneously, they turned and went back to the door by which they had
entered the flat. It was locked.

"We've been trapped," said Gertrude in a low voice. "Let's look through
the place."

They began another search, opening closet doors and looking into
wardrobes and cupboards and under the furniture. They went to the
kitchen and tried the door into the back passage; but that, too, was
locked. There was nobody else in the flat; there was no possible way of
getting out.

"The windows," said Gertrude. "There should be fire escapes."

But there were not. They could not raise the windows from the bottom,
either, although they could lower them slightly from the top for air.
They climbed up and peeped over, only to discover that they were seven
stories from the ground, and looked only into a light-well. The flat
across from them was unoccupied.

They looked at their watches. It was ten o'clock--even then the churches
were chiming out the hour.

"Let us look for a note, or some intimation of what to expect," said
Mary. "I wonder if they are going to keep us here all night."

"It's a trick," said Gertrude. "There's no knowing how long we may
stay--nor what will happen to us. I'm glad I thought of this before I
started out alone tonight." And she produced a small revolver from her
coat pocket.

"Mercy!" cried Mary, "do you carry that? Would you know how to use it?"

"I carried it when father and I walked through the Pyrenees a few years
ago," answered Gertrude. "I used it once--to good advantage--and I could
again, if I had to," she added. "Now, let us see what the gods--or the
other thing--have provided."

Another search showed them that their flat was well-provisioned,
well-furnished, heated and lighted. There were a few books and
magazines, a piano, a writing desk, even a pack of playing cards.

"We may have to resort to solitaire yet," laughed Mary. "Though nothing
short of imprisonment could induce me to fool away my time with the
silly game."

"Well, they have provided for an indefinite stay, I fear," said
Gertrude. "Somehow, I have a feeling that we are not going to get out
easily. We must think up some way of letting our friends know we are
here."

But their jailers had looked out for that. They could hang towels from
their upper windows, but to what end, since these could not be seen?

There was no stationery in the desk, but Mary had a poc