"What are their names?"

"Suzanne and Gertrude."

"One of them has red hair, has she not?"

"Yes, Gertrude."

"Have you known her long?"

"Her sister has always been with me ... and so has Gertrude, for years... . She is devotion and honesty personified... ."

"In short, you will answer for her?"

"Oh, absolutely!"

"Very well ... very well."

It was half-past seven and the daylight was beginning to wane when the taxi-cab reached the House of Retreat. Without troubling about his companion, the chief detective rushed into the porter's lodge:

"Mrs. Kesselbach's maid has just come in, has she not?"

"Whom do you mean, the maid?"

"Why, Gertrude, one of the two sisters."

"But Gertrude can't have been out, sir. We haven't seen her go out."

"Still some one has just come in."

"No, sir, we haven't opened the door to anybody since--let me see--six o'clock this evening."

"Is there no other way out than this gate?"

"No. The walls surround the estate on every side and they are very high.

"Mrs. Kesselbach, we will go to your house, please."

They all three went. Mrs. Kesselbach, who had no key, rang. The door was answered by Suzanne, the other sister.

"Is Gertrude in?" asked Mrs. Kesselbach.

"Yes, ma'am, in her room."

"Send her down, please," said the chief detective.

After a moment, Gertrude came downstairs, looking very attractive and engaging in her white embroidered apron.

She had, in point of fact, a rather pretty face, crowned with red hair.

M. Lenormand looked at her for a long time without speaking, as though he were trying to read what lay behind those innocent eyes.

He asked her no questions. After a minute, he simply said:

"That will do, thank you. Come, Gourel."

He went out with the sergeant and, at once, as they followed the darkling paths of the garden, said:

"That's the one!"

"Do you think so, chief? She looked so placid!"

"Much too placid. Another would have been astonished, would have wanted to know why I sent for her. Not this one! Nothing but the concentrated effort of a face that is determined to smile at all costs. Only, I saw a drop of perspiration trickle from her temple along her ear."

"So that ... ?

"So that everything becomes plain. Gertrude is in league with the two ruffians who are conspiring round the Kesselbach case, in order either to discover and carry out the famous scheme, or to capture the widow's millions. No doubt, the other sister is in the plot as well. At four o'clock, Gertrude, learning that I know of the advertisement in the _Journal_, takes advantage of her mistress's absence, hastens to Paris, finds Ribeira and the man in the soft hat and drags them off to the Palais, where Ribeira annexes Master Steinweg for his own purposes."

He reflected and concluded:

"All this proves, first, the importance which they attach to Steinweg and their fear of what he may reveal; secondly, that a regular plot is being hatched around Mrs. Kesselbach; thirdly, that I have no time to lose, for the plot is ripe."

"Very well," said Gourel, "but one thing remains unexplained. How was Gertrude able to leave the garden in which we now are and to enter it again, unknown to the porter and his wife?"

"Through a secret passage which the rogues must have contrived to make quite recently."

"And which would end, no doubt," said Gourel, "in Mrs. Kesselbach's house."

"Yes, perhaps," said M. Lenormand, "perhaps ... But I have another idea."

They followed the circuit of the wall. It was a bright night; and, though their two forms were hardly distinguishable, they themselves could see enough to examine the stones of the walls and to convince themselves that no breach, however skilful, had been effected.

"A ladder, very likely?" suggested Gourel.

"No, because Gertrude is able to get out in broad daylight. A communication of the kind I mean can evidently not end out of doors. The entrance must be concealed by some building already in existence."

"There are only the four garden-houses," objected Gourel, "and they are all inhabited."

"I beg your pardon: the third, the Pavillon Hortense, is not inhabited."

"Who told you so?"

"The porter. Mrs. Kesselbach hired this house, which is near her own, for fear of the noise. Who knows but that, in so doing, she acted under Gertrude's influence?"

He walked round the house in question. The shutters were closed. He lifted the latch of the door, on the off-chance; the door opened.

"Ah, Gourel, I think we've struck it! Let's go in. Light your lantern.

... Oh, the hall... . the drawing-room ... the dining-room ...