had found means to send in his stead an innocent victim, Valgrand, the actor.
"When will you begin to draw in your net?" inquired Fandor.
Juve motioned to his companion to be silent and listen.
"Fandor, you hear what that man's singing; the one drinking at the bar?"
"Yes, 'The Blue Danube.'"
"Well, that gives me the answer. We shall soon be on Loupart's tracks. By the way, are you armed?"
"If you won't run me in for carrying concealed weapons I'll confess that Baby Browning is in my pocket."
"Good. Now, then, listen to my directions. Loupart was seen at the markets this morning by two of my watchers, and you may be sure he hasn't been lost sight of since. Reports I have received indicate that he will presumably go to the Chateaudun cross-roads and from there to the Place Pigalle, in the direction of Doctor Chaleck's house. We shall nab him at the cross-roads. Needless to say we are not going to keep together. As soon as our man comes in sight you will pass on ahead, walking at his pace on the same pavement and without turning round."
"And if Loupart doesn't appear?"
"Why then — " began Juve. "The deuce! There's another customer whistling 'The Blue Danube.' It's time to be off."
"Are those your agents whistling?" asked Fandor, as they left the shop.
"No."
"What! Isn't it a signal?"
"It is, and you'll be able to find your trail by the passers-by who whistle that air."
While talking, the journalist and the detective arrived at the Chateaudun cross-roads. Juve cast an eye over the ground.
"It's six o'clock. Be off and prowl around Notre Dame de Lorette. Loupart will probably come out of that wine-shop you see to the right. You can easily recognise him by his height and a scar on his left cheek."
"Look here, Juve, why should these people whistle 'The Blue Danube' if they are not detectives?"
Juve smiled. "It's quite simple. If you whistle a popular tune in a crowd, some one is bound to take it up. Well, the two men I put to watching Loupart this morning were whistling this same tune, and now we are meeting persons who caught the air."
Fandor crossed the road and proceeded toward Notre Dame de Lorette to the post the detective had allotted to him. The man hunt was about to begin.
III
BEHIND THE CURTAIN
The Cité Frochot is shut in by low stone walls, topped by grating round which creepers intertwine.
The entry to its main thoroughfare, shaded by trees and lined with small private houses, is not supposed to be public, and a porter's lodge to the right of the entrance is intended to enforce its private character.
It was about seven in the evening. As the fine spring day drew to a close, Fandor reached the square of the Cité. For an hour past the journalist had been wholly engaged in keeping track of the famous Loupart, who, after leaving the saloon, had sauntered up the Rue des Martyrs, his hands in his pockets and a cigarette in his mouth.
Fandor allowed him to pass at the corner of the Rue Claude, and from there on kept him in view.
Juve had completely disappeared.
As Loupart, followed by Fandor, was about to enter the Cité Frochot, an exclamation made them both turn.
Fandor perceived a poorly dressed man anxiously searching for something in the gutter. A curious crowd had instantly collected, and word was passed round that the lost object was a twenty-five-franc gold piece.
Fandor, joining the crowd, was pushed close to the man, who quickly whispered:
"Idiot! Keep out of the Cité."
The owner of the gold piece was no other than the detective. Then, under cover of loud complaint, Juve muttered to Fandor, "Let him go! Watch the entrance to the Cité!"
"But," objected Fandor in the same key, "what if I lose sight of him?"
"No fear of that. The doctor's house is the second on the right." The hooligan, who had for a moment drawn near the crowd, was now heading straight for the Cité.
Juve went on: "In a quarter of an hour at the latest join me again, 27 Rue Victor Massé."
"And if Loupart should enter the Cité in the meantime?"
"Come straight back to me."
Fandor was moving off when Juve addressed him out loud: "Thank you, kind gentlemen! But as you are so charitable, give me something more for God's sake."
The other drew near the pretended beggar and Juve added:
"If anyone questions you as you pass through, say you are going to Omareille, the decorator's; you'll find me on the stairs."
Some moments later the little crowd had melted away and a policeman, arriving as usual too late, wondered what had been going on.
Fandor carried out Juve's instructions to the letter. Hiding behind a sentry box he kept an eye on the doctor's house, but nothing out of the way happened. Loupart had vanished, although he was probably not far away. When the fifteen minutes were up Fandor left his post and entered No. 27 Rue Victor Massé. As he reached the third floor he heard Juve's voice:
"Is that you, lad?"
"Yes."
"The porter didn't question you?"
"I've seen no one."
"All right, come up here."
Juve was seated at a hall window examining Doctor Chaleck's house through a field glass.
"You've not seen Loupart go in?" he inquired as Fandor joined him.
"Not while I was on watch."
"It's well to know one's Paris and have friends everywhere, isn't it?" continued Juve. "It occurred to me quite suddenly that this might be an excellent place from where to follow citizen Loupart's doings. You would have spoiled everything if you had followed him into the Cité. That's why I devised my little scheme to hold you back."
"You are right," admitted Fandor, who, the next moment, gave a jump as Juve's hand gripped him hard.
"Look, Fandor! The bird is going into the cage!"
The journalist, excited, saw a figure already familiar to him in the act of slipping into the little garden which separated Dr. Chaleck's house from the main thoroughfare.
The detective went on: "There he goes, skirting the house until he reaches the little door hidden in the wall. What's he up to now? Ah! He's
