At the far end of the Rue de Rome Fandor halted. "After all," he thought, "maybe I am going straight into a trap. Who sent me the letter? Who is this M. Mahon? I never heard of him. Why this menacing phrase, 'Come, if you take any interest in the affairs of Lady B—— and F——.' Oh, if only I could take counsel of Juve!"

But for the last fortnight, since the ill-starred affair of Nogent and the almost incredible discovery he had made that Lady Beltham was still alive, Fandor had not seen Juve. He had been to the SÛretÉ a number of times, but Juve had vanished.

Fandor stopped before a private house on the Boulevard Pereire North. He passed in through the outer hall and reached the porter's lodge.

"Madame, have you a tenant here named Mahon?"

The porteress came forward.

"M. Mahon? To be sure—fifth floor on the right."

"Thank you. I should like to ask a few questions about him. I have come—to negotiate an insurance policy for him and I should like to know about the value of the furniture in his rooms. What sort of a man is this M. Mahon? About how old is he?"

Fandor had, by pure professional instinct, found the best device in the world. There is not a porteress who has not many times enlightened insurance agents.

"Why, sir, M. Mahon has lived here only a month or six weeks. He can scarcely be very well off, for when he moved in I did not see any fine furniture go up. I believe for that matter he is an old cavalry officer, and, in the army nowadays, folks scarcely make fortunes."

"That's true enough," assented Fandor.

"Anyhow he is a very charming man, an ideal lodger. To begin with, he is infirm, almost paralysed in both legs. I believe he never goes out of an evening. And then he never has any visitors except two young fellows who are serving their time in the army."

"Are they with him now?"

"No, sir, they never come till three or four in the afternoon."

Fandor slipped a coin into the woman's hand and went upstairs. He rang at the door and was surprised at a strange, soft rolling sound.

"Oh, I know," he thought; "the poor man must move about his rooms in a rubber-tired wheel chair."

He was not mistaken. Scarcely was the door opened when he caught sight of an old man of much distinction seated in a wheel chair. This invalid greeted the journalist pleasantly.

"M. Fandor?"

"The same, sir."

M. Mahon pushed forward his chair and motioned to his visitor to come in.

Fandor entered a room in which the curtains were closely drawn and which was brilliantly illuminated with electric lights, although it was the middle of the afternoon. Was it a trap? The journalist instinctively hesitated in the doorway. But behind him a cordial voice called:

"Come in, you all kinds of an idiot!"

The door clicked behind him and the invalid, getting out of his chair, burst into a fit of laughter.

"Juve! Juve!"

"As you see!"

"Bah, what farce are you playing here? Why this lit-up room?"

"All for very good reasons. If you will be kind enough to take a seat, I will explain."

Fandor dropped into a chair staring at Juve, who continued:

"When you came back the other day and told me that unlikely yarn about Lady Beltham being alive, I decided to try new methods. First of all, I became a cavalry officer, then I got this wheel chair and moved into this apartment."

As Juve paused, Fandor, more and more amazed, inquired:

"But your reason for all this!"

"Just wait! The day after the Dixon business, I put three of my best men on the track of the American. I had a notion he would want to see Josephine again, and I was not mistaken. She came back to justify herself in his eyes. The story ended as might have been foreseen. Michel, who brought me the news, said that Josephine had agreed to become Dixon's mistress."

"The deuce!"

"Oh, there is nothing to be surprised at that. Michel made arrangements to learn all the details. Josephine is to live at 33 C in Boulevard Pereire South; that is, to the right of the railway line, fourth floor. Here we are at 24 B Boulevard Pereire North, to left of the railway, fifth floor, and just opposite."

"And what does this old M. Mahon do, Juve?"

Juve smiled.

"You are going to see, my lad."

He settled himself again in the wheel chair, drew a heavy rug over his knees and became once more the old invalid.

"My dear friend, will you open the door for me?"

Fandor laughingly complied, and Juve wheeled himself into another room.

"You see I have plenty of air here thanks to this balcony upon which I can wheel my chair. Would you be good enough to pass me that spy-glass?"

Juve pointed the glass toward the far end of Boulevard Pereire, in the direction of Poste Maillot.

"Mlle. Josephine has lately had a craze for keeping her nails polished."

"But you are not looking toward the house opposite, you are looking in a contrary direction!"

Juve laid his spy-glass on his knees and laughed.

"I expected you to make that remark. See, those glasses at the end are only for show, inside is a whole system of prisms. With this perspective you see not in front of you, but on one side. In other words, when I point it at the far end of the boulevard, what I am really looking at is the house opposite."

Fandor was about to congratulate his friend on this new specimen of his ingenuity, but Juve did not give him time. He startled the journalist by suddenly asking him:

"Tell me, do you love the army?"

"Why?"

"Because I think those two soldiers you see over there are coming."

"To see you," added Fandor.

"How do you know?"

"From your porteress."

"You pumped her?"

"I did. I got her to talk a bit about that excellent M. Mahon."

Juve laughed:

"Confound you!"

With a quick movement Fandor, at the detective's request, drew back the wheel chair and shut the window.

"You understand," explained Juve, "there is nothing to surprise my neighbours in my having two soldiers to visit me. But I don't care for third persons to hear what they say to me." There was a ring at the apartment door. "Go and open, Fandor. I don't leave my cripple's chair for them; people can see through the curtains."

Shown in by Fandor, the soldiers shook hands with Juve and took seats opposite him.

"Do you recognise Michel and LÉon?"

"Oh, perfectly!" cried Fandor, "but why this disguise?"

"Because no heed is paid to uniforms, there are soldiers everywhere, and also it is not easy to recognise a civilian suddenly appearing in uniform. What is fresh, Michel?"

"Something pretty serious, sir. According to your instructions we have been shadowing the Superior of the Nogent Convent."

"Well, what have you discovered?"

"Every Tuesday evening the Superior leaves Nogent and goes to Paris."

"Where?"

"To one of the branches of her religious house in the Boulevard Jourdan."

"No. 180?"

Michel was dumbfounded.

"Yes, sir, you knew?"

"No," said Juve, coldly. "What does she do at this branch?"

"There are four or five old nuns there. The Superior spends Tuesday night there and on Wednesday goes back to Nogent about one in the afternoon."

"And you know no more than that?"

"No, sir. Must we go on with the shadowing?"

"No, it is not worth while. Return to the Prefecture and report to M. Havard."

When the two men had left, Fandor turned to Juve.

"What do you make of it?"

Juve shrugged his shoulders.

"Michel is an idiot. That house has two exits; one to the Boulevard, the other to waste ground that leads to the fortifications. The Superior, or Lady Beltham, goes there to change her dress, and then hastens to some prearranged meeting elsewhere. The house at Neuilly will bear watching."