ll. You had
better take the measurements of it, inspector. Here's a foot-rule for
you. I make a point of carrying this foot-rule about with me, your
Grace. You would be surprised to learn how often it has come in useful."

He took a little ivory foot-rule from his waist-coat pocket, and gave
it to the inspector, who fell on his knees and measured the footprint
with the greatest care.

"I must take a careful look at that house they're building. I shall
find a good many traces there, to a dead certainty," said M. Formery.

The inspector entered the measurements of the footprint in his
note-book. There came the sound of a knocking at the front door.

"I shall find footprints of exactly the same dimensions as this one at
the foot of some heap of plaster beside that house," said M. Formery;
with an air of profound conviction, pointing through the window to the
house building beyond the garden.

A policeman opened the door of the drawing-room and saluted.

"If you please, sir, the servants have arrived from Charmerace," he
said.

"Let them wait in the kitchen and the servants' offices," said M.
Formery. He stood silent, buried in profound meditation, for a couple
of minutes. Then he turned to the Duke and said, "What was that you
said about a theft of motor-cars at Charmerace?"

"When he received the letter from Arsene Lupin, M. Gournay-Martin
decided to start for Paris at once," said the Duke. "But when we sent
for the cars we found that they had just been stolen. M.
Gournay-Martin's chauffeur and another servant were in the garage
gagged and bound. Only an old car, a hundred horse-power Mercrac, was
left. I drove it to Paris, leaving M. Gournay-Martin and his family to
come on by train."

"Very important--very important indeed," said M. Formery. He thought
for a moment, and then added. "Were the motor-cars the only things
stolen? Were there no other thefts?"

"Well, as a matter of fact, there was another theft, or rather an
attempt at theft," said the Duke with some hesitation. "The rogues who
stole the motor-cars presented themselves at the chateau under the name
of Charolais--a father and three sons--on the pretext of buying the
hundred-horse-power Mercrac. M. Gournay-Martin had advertised it for
sale in the Rennes Advertiser. They were waiting in the big hall of the
chateau, which the family uses as the chief living-room, for the return
of M. Gournay-Martin. He came; and as they left the hall one of them
att