d that it about reached the top of the cafe door. He
stole quietly down and let himself out, leaving the door unlatched. The
door to the apartments was at the extreme edge of the building, while
the cafe doors were in the middle, with large windows on each side. As
he came round to the front, his heart almost ceased to beat when a
voice from the cafe door said--

"What do you want? What are you doing here at this hour?"

The policeman had become so much a part of the pavement in Dupre's mind
that he had actually forgotten the officer was there night and day.
Dupre allowed himself the luxury of one silent gasp, then his heart
took up its work again.

"I was looking for you," he said quietly. By straining his eyes he
noticed at the same moment that the cord dangled about a foot above the
policeman's head, as he stood in the dark doorway.

[Illustration: THE CORD DANGLED ABOUT A FOOT ABOVE THE POLICEMAN'S
HEAD]

"I was looking for you. I suppose you don't know of any--any chemist's
shop open so late as this? I have a raging toothache and can't sleep,
and I want to get something for it."

"Oh, the chemist's at the corner is open all night. Ring the bell at
the right hand."

"I hate to disturb them for such a trifle."

"That's what they're there for," said the officer philosophically.

"Would you mind standing at the other door till I get back? I'll be as
quick as I can. I don't wish to leave it open unprotected, and I don't
want to close it, for the _concierge_ knows I'm in and he is
afraid to open it when any one rings late. You know me, of course; I'm
in No. 16."

"Yes, I recognise you now, though I didn't at first. I will stand by
the door until you return."

Dupre went to the corner shop and bought a bottle of toothache drops
from the sleepy youth behind the counter. He roused him up however, and
made him explain how the remedy was to be applied. He thanked the
policeman, closed the door, and went up to his room. A second later the
cord was cut at the window and quietly pulled in.

Dupre sat down and breathed hard for a few moments.

"You fool!" he said to himself; "a mistake or two like that and you are
doomed. That's what comes of thinking too much on one branch of your
subject. Another two feet and the string would have been down on his
nose. I am certain he did not see it; I could hardly see it myself,
looking for it. The guarding of the side door was an inspiration. But
I must think well over every