Coucou had not taken time to change his clothes when he presented himself to Madame Caraman on his return home, and the worthy woman uttered a cry of astonishment.

"What is the meaning of this?" she asked. "I think that we have more serious things to think of than masquerading."

"Come, do not speak before you know everything," replied the Zouave; and in a few words he told her the story of his disguise.

"Where can Monsieur Sabran be?" asked Madame Caraman.

"What!" exclaimed Coucou, "where is he then?"

"I haven't seen him, nor Fanfaro, nor Bobichel since."

"Impossible! Are they still in Jane's room?"

"Perhaps."

"I cannot understand it, and—"

A hollow noise caused Coucou to keep silent. He and Madame Caraman looked at each other in terror.

"What can that be?" asked Madame Caraman.

Before Coucou could answer the question, the noise was repeated.

"The noise comes from the right side," said Coucou, who had been listening; "let us hurry to Gontram and Fanfaro, and call their attention to it."

Mamma Caraman nodded, and they both went to Jane's room.

It was empty!

"This is getting worse and worse," cried Coucou, anxiously. "Do you know what I think? This room has a secret exit, and through it Jane, the vicomte, and Gontram and his comrades have disappeared."

"What are you going to do?"

"Break down the house if necessary," said Coucou, beginning to trample upon the floor.

"But you are ruining the carpet!" cried Mamma Caraman.

The sound of the door-bell at this minute prevented Coucou from replying. In front of the door stood Carmen.

"Thank Heaven you have come, mademoiselle."

"You haven't found Gontram yet?"

"No."

"Monsieur Gontram and his comrades are in subterranean chambers in this house."

"Knock at the walls, Coucou," said Madame Caraman, "and then we can wait for an answer."

Coucou knocked three times with a hammer against the wall. At the end of the second knock came back in answer twenty-five.

"What does that mean?" asked Coucou, in affright.

"I know," cried Carmen; "twenty-five knocks signify the letters of the alphabet!"

"Then we must answer to show that we understand the language," said Madame Caraman. "Coucou—quick—twenty-five knocks."

The Zouave did as he was told, and the answer came back in one knock which meant "yes."

Nine further knocks followed.

"I," said Carmen.

Nineteen knocks.

"S," whispered Carmen.

Seven knocks.

"G."

Ten knocks.

"J."

Two knocks.

"B."

Twenty knocks.

"T."

Carmen now read the meaning of this:

"There is an iron door under the wall decoration."

Coucou soon found the secret door.

At the end of five minutes Fanfaro, Bobichel and Gontram were again with their friends. In a few words Carmen related what had brought her there, and showed the letter she had taken from Larsagny.

"In Courbevoie!" cried Gontram. "How shall we find Spero there?"

"I know the house," said Carmen; "it belongs to the banker, and I believe we shall find the vicomte there."

"May God grant it."

Ten minutes later they were all on the road to Courbevoie.