The detective’s amour-propre was clearly aroused; his professional zeal was inspired; he found himself before a great crime—­one of those crimes which triple the sale of the Gazette of the Courts.  Doubtless many of its details escaped him:  he was ignorant of the starting-point; but he saw the way clearing before him.  He had surprised Plantat’s theory, and had followed the train of his thought step by step; thus he discovered the complications of the crime which seemed so simple to M. Domini.  His subtle mind had connected together all the circumstances which had been disclosed to him during the day, and now he sincerely admired the old justice of the peace.  As he gazed at his beloved portrait, he thought, “Between the two of us—­this old fox and I—­we will unravel the whole web.”  He would not, however, show himself to be inferior to his companion.

“Monsieur,” said he, “while you were questioning this rogue, who will be very useful to us, I did not lose any time.  I’ve been looking about, under the furniture and so on, and have found this slip of paper.”

“Let’s see.”

“It is the envelope of the young lady’s letter.  Do you know where her aunt, whom she was visiting, lives?”

“At Fontainebleau, I believe.”  “Ah; well, this envelope is stamped ‘Paris,’ Saint-Lazare branch post-office.  I know this stamp proves nothing—­”

“It is, of course, an indication.”

“That is not all; I have read the letter itself—­it was here on the table.”

M. Plantat frowned involuntarily.

“It was, perhaps, a liberty,” resumed M. Lecoq, “but the end justifies the means.  Well, you have read this letter; but have you studied it, examined the hand-writing, weighed the words, remarked the context of the sentences?”

“Ah,” cried Plantat, “I was not mistaken then—­you had the same idea strike you that occurred to me!”

And, in the energy of his excitement he seized the detective’s hands and pressed them as if he were an old friend.  They were about to resume talking when a step was heard on the staircase; and presently Dr. Gendron appeared.

“Courtois is better,” said he, “he is in a doze, and will recover.”

“We have nothing more, then, to keep us here,” returned M. Plantat.  “Let’s be off.  Monsieur Lecoq must be half dead with hunger.”

As they went away, M. Lecoq slipped Laurence’s letter, with the envelope, into his pocket.

X

M. Plantat’s house was small and narrow; a philosopher’s house.  Three large rooms on the ground-floor, four chambers in the first story, an attic under the roof for the servants, composed all its apartments.  Everywhere the carelessness of a man who has withdrawn from the world into himself, for years, ceasing to have the least interest in the objects which surround him, was apparent.  The furniture was shabby, though it had been elegant; the mouldings had come off, the clocks had ceased to keep time, the chairs showed the stuffing of their cushions, the curtains, in places, were faded by the sun.  The library alone betrayed a daily care and attention.