a ruse."

"Is that so?" said Guerchard.

"Is there any way I can help you, sir?" said policeman.

"Yes," said Guerchard. "Take up your post outside that door and admit
no one but M. Formery, the inspector, Bonavent, or Dieusy, without
consulting me." And he pointed to the drawing-room door.

"Shan't I admit the Duke of Charmerace? He's taking a great interest in
this affair," said the policeman.

"The Duke of Charmerace? Oh, yes--admit the Duke of Charmerace," said
Guerchard.

The policeman went to his post of responsibility, a proud man.

Hardly had the door closed behind him when Guerchard was all
activity--activity and eyes. He examined the ladder, the gaps on the
wall from which the pictures had been taken, the signatures of Arsene
Lupin. The very next thing he did was to pick up the book which the
Duke had set on the top of the footprint again, to preserve it; and he
measured, pacing it, the distance between the footprint and the window.

The result of this measuring did not appear to cause him any
satisfaction, for he frowned, measured the distance again, and then
stared out of the window with a perplexed air, thinking hard. It was
curious that, when he concentrated himself on a process of reasoning,
his eves seemed to lose something of their sharp brightness and grew a
little dim.

At last he seemed to come to some conclusion. He turned away from the
window, drew a small magnifying-glass from his pocket, dropped on his
hands and knees, and began to examine the surface of the carpet with
the most minute care.

He examined a space of it nearly six feet square, stopped, and gazed
round the room. His eyes rested on the fireplace, which he could see
under the bottom of the big tapestried fire-screen which was raised on
legs about a foot high, fitted with big casters. His eyes filled with
interest; without rising, he crawled quickly across the room, peeped
round the edge of the screen and rose, smiling.

He went on to the further drawing-room and made the same careful
examination of it, again examining a part of the surface of the carpet
with his magnifying-glass. He came back to the window to which the
ladder had been raised and examined very carefully the broken shutter.
He whistled softly to himself, lighted a cigarette, and leant against
the side of the window. He looked out of it, with dull eyes which saw
nothing, the while his mind worked upon the facts he had discovered.

He had stood there plung