He wanted a moment to think, and it was essential that he should inhale as little of the ammonia as possible while he decided what to do.

The situation was a terrifying one. To a man less courageous than Nick Carter, it might have appeared hopeless.

“The window!” he muttered. “I know how I got out of the other cellar, by Patsy helping me from the outside. This time I’ll have to get it open by my own efforts.”

He drew from his pocket the heavy jackknife without which he never went out. Included in its tools was a miniature brace and bit. He fitted this for use as he crawled toward the window.

With his handkerchief tied over his mouth and nose, to keep out as much of the gas he could, Nick got his brace and bit ready for action and pulled himself to his feet.

A few seconds of work bored a hole through the wood. It was old and rotten, and the bit was keen and highly tempered.

The hole was by the side of a nail, whose point Nick had discerned coming through the wood.

“Two more holes, at the other nails, and we’ll be through,” he muttered. “If only I can hold out so long!”

It was a narrow squeak. But when a man is fighting for his life, he’ll keep on against odds, no matter what sort of contest he may have on his hands.

Just as Nick felt that he could not bear the awful pressure of the gas on his lungs another instant, he pushed the boards out of the opening.