great service to him
in a civil action, while I was acting as secretary to Maitre Barbet
Delatour. Monsieur Robert Darzac, who was at that time about forty years
of age, was a professor of physics at the Sorbonne. He was intimately
acquainted with the Stangersons, and, after an assiduous seven years'
courtship of the daughter, had been on the point of marrying her. In
spite of the fact that she has become, as the phrase goes, "a person
of a certain age," she was still remarkably good-looking. While I was
dressing I called out to Rouletabille, who was impatiently moving about
my sitting-room:

"Have you any idea as to the murderer's station in life?"

"Yes," he replied; "I think if he isn't a man in society, he is, at
least, a man belonging to the upper class. But that, again, is only an
impression."

"What has led you to form it?"

"Well,--the greasy cap, the common handkerchief, and the marks of the
rough boots on the floor," he replied.

"I understand," I said; "murderers don't leave traces behind them which
tell the truth."

"We shall make something out of you yet, my dear Sainclair," concluded
Rouletabille.

CHAPTER III. "A Man Has Passed Like a Shadow Through the Blinds"

Half an hour later Rouletabille and I were on the platform of the
Orleans station, awaiting the departure of the train which was to take
us to Epinay-sur-Orge.

On the platform we found Monsieur de Marquet and his Registrar, who
represented the Judicial Court of Corbeil. Monsieur Marquet had spent
the night in Paris, attending the final rehearsal, at the Scala, of a
little play of which he was the unknown author, signing himself simply
"Castigat Ridendo."

Monsieur de Marquet was beginning to be a "noble old gentleman."
Generally he was extremely polite and full of gay humour, and in all
his life had had but one passion,--that of dramatic art. Throughout
his magisterial career he was interested solely in cases capable of
furnishing him with something in the nature of a drama. Though he might
very well have aspired to the highest judicial positions, he had
never really worked for anything but to win a success at the romantic
Porte-Saint-Martin, or at the sombre Odeon.

Because of the mystery which shrouded it, the case of The Yellow
Room was certain to fascinate so theatrical a mind. It interested him
enormously, and he threw himself into it, less as a magistrate eager
to know the truth, than as an amateur of dramatic embrogl