“Hurry, my child,” urged Coquenil, and working madly with a piece of stick that he had wrenched from one of the logs, he met each feather of smoke with a strip of cloth, stuffing the cracks with shreds of garments, with Alice’s veil and hat ribbon, with the lining of his coat, then with the body of it, with the waist of her dress, with his socks, with her stockings, and still the smoke came through.

“We must stop this,” he cried, and tearing the shirt from his shoulders, he ripped it into fragments and wedged these tight between the logs.  The smoke seemed to come more slowly, but—­it came.

“We must have more cloth,” he said gravely.  “It’s our only chance, little friend.  I’ll put out the candle!  There!  Let me have—­whatever you can and—­be quick!”

Again he worked with frantic haste, stuffing in the last shreds and rags that could be spared from their bodies, whenever a dull glow from the other side revealed a crack in the barricade.  For agonized moments there was no sound in that tomblike chamber save Alice’s quick breathing and the shrieking tear of garments, and the ramming thud of the stick as Coquenil wedged cloth into crannies of the logs.

“There,” he panted, “that’s the best we can do. Now it’s up to God!”

For a moment it seemed as if this rough prayer had been answered.  There were no more points in the barricade that showed a glow beyond and to Coquenil, searching along the logs in the darkness by the sense of smell, there was no sign of smoke coming through.

“I believe we have stopped the draught,” he said cheerfully; “as a final touch I’ll hang that cloak of yours over the whole thing,” and, very carefully, he tucked the white garment over the topmost logs and then at the sides so that it covered most of the barricade.

“You understand that a fire cannot burn without air,” he explained, “and it must be air that comes in from below to replace the hot air that rises.  Now I couldn’t find any openings in that large room except two little ventilators near the ceiling, so if that fire is going to burn, it must get air from this room.”

“Where does this room get its air from?” asked Alice.

Coquenil thought a moment.  “It gets a lot under that iron door, and—­there must be ventilating shafts besides.  Anyhow, the point is, if we have blocked this passage between the rooms we have stopped the fire from turning, or, anyhow, from burning enough to do us any harm.  You see these logs are quite cold.  Feel them.”

Alice groped forward in the darkness toward the barricade and, as she touched the logs, her bare arm touched Coquenil’s bare arm.

Suddenly a faint sound broke the stillness and the detective started violently.  He was in such a state of nervous tension that he would have started at the rustle of a leaf.

“Hark!  What is that?”

It was a low humming sound that presently grew stronger, and then sang on steadily like a buzzing wheel.