"Ah!" muttered Lupin, with a choking throat. "It was a letter from
Gilbert!"

He stood motionless, a little pale, with drawn features. There was no
doubt about it: the letter was from Gilbert. It was the form of address
which, by Lupin's orders, Gilbert had used for years in corresponding
with him. Gilbert had at last--after long waiting and by dint of
endless artifices--found a means of getting a letter posted from his
prison and had hastily written to him. And now the letter was
intercepted! What did it say? What instructions had the unhappy
prisoner given? What help was he praying for? What stratagem did he
suggest?

Lupin looked round the room, which, contrary to the drawing-room,
contained important papers. But none of the locks had been forced; and
he was compelled to admit that the woman had no other object than to get
hold of Gilbert's letter.

Constraining himself to keep his temper, he asked:

"Did the letter come while the woman was here?"

"At the same time. The porter rang at the same moment."

"Could she see the envelope?"

"Yes."

The conclusion was evident. It remained to discover how the visitor had
been able to effect her theft. By slipping from one window to the other,