written in large capitals:

"Everything you are doing is useless and dangerous... Give it up."

Victoire uttered one moan and fainted. As for Lupin, he felt himself
blush up to his eyes, as though he had been grossly insulted. He
experienced all the humiliation which a duellist would undergo if he
heard the most secret advice which he had received from his seconds
repeated aloud by a mocking adversary.

However, he held his tongue. Victoire went back to her work. As for
him, he remained in his room all day, thinking.

That night he did not sleep.

And he kept saying to himself:

"What is the good of thinking? I am up against one of those problems
which are not solved by any amount of thought. It is certain that I am
not alone in the matter and that, between Daubrecq and the police, there
is, in addition to the third thief that I am, a fourth thief who is
working on his own account, who knows me and who reads my game clearly.
But who is this fourth thief? And am I mistaken, by any chance? And...
oh, rot!... Let's get to sleep!..."

But he could not sleep; and a good part of the night went in this way.

At four o'clock in the morning he seemed to hear a noise in the house.
He jumped up quickly and, from the top of the staircase, saw Daubrecq
go down the first flight and turn toward the garden.