“A quarter to seven,” he reflected; then, turning to the right, he walked quickly to a little wine shop with flowers in the windows, the Tavern of the Three Wise Men, an interesting fragment of old-time Paris that offers its cheery but battered hospitality under the very shadow of the great cathedral.

“Ah, I thought so!” he muttered, as he recognized Papa Tignol at one of the tables on the terrace.  And approaching the old man, he said in a low tone:  “I want you.”

Tignol looked up quickly from his glass, and his face lighted.  “Eh, M. Paul again!”

“I must see M. Pougeot,” continued the detective.  “It’s important.  Go to his office.  If he isn’t there, go to his house.  Anyhow, find him and tell him to come to me at once.  Hurry on; I’ll pay for this.”

“Shall I take an auto?”

“Take anything, only hurry.”

“And you want me at nine o’clock?”

Coquenil shook his head.  “Not until to-morrow.”

“But the news you were going to tell me?”

“There’ll be bigger news soon.  Oh, run across to the church and tell Bonneton that he needn’t come either.”

“I knew it, I knew it,” chuckled Papa Tignol, as he trotted off.  “There’s something doing!”

[Illustration:  “‘I want you,’ he said in a low voice.”]

With this much arranged, Coquenil, after paying for his friend’s absinthe, strolled over to a cab stand near the statue of Henri IV and selected a horse that could not possibly make more than four miles an hour.  Behind this deliberate animal he seated himself, and giving the driver his address, he charged him gravely not to go too fast, and settled back against the cushions to comfortable meditations.  “There is no better way to think out a tough problem,” he used to insist, “than to take a very long drive in a very slow cab.”

It may have been that this horse was not slow enough, for forty minutes later Coquenil’s frown was still unrelaxed when they drew up at the Villa Montmorency, really a collection of villas, some dozens of them, in a private park near the Bois de Boulogne, each villa a garden within a garden, and the whole surrounded by a great stone wall that shuts out noises and intrusions.  They entered by a massive iron gateway on the Rue Poussin and moved slowly up the ascending Avenue des Tilleuls, past lawns and trees and vine-covered walls, leaving behind the rush and glare of the city and entering a peaceful region of flowers and verdure where Coquenil lived.

The detective occupied a wing of the original Montmorency chateau, a habitation of ten spacious rooms, more than enough for himself and his mother and the faithful old servant, Melanie, who took care of them, especially during these summer months, when Madame Coquenil was away at a country place in the Vosges Mountains that her son had bought for her.  Paul Coquenil had never married, and his friends declared that, besides his work, he loved only two things in the world—­his mother and his dog.