Never did three young men face a more terrible or more horribly gruesome situation. Here they were, locked in a natural dungeon behind a wall of dirt and rock probably four or five feet thick. Not only that, but the cave already contained the bodies of six men whose fixed and glassy eyes stared at them as though in mockery and warning, and the already foul air was becoming more stifling every moment.

In a dull way they realized that they probably could not survive more than two or three maddening hours in that death chamber.

"It may not be so bad as it seems," said Lieutenant Mackinson in a voice that seemed unnatural in that vault. "Perhaps it was only a slight cave-in."

He flashed his light about the hole. It was difficult to tell where the opening had been.

"Joe and Frank Hoskins!" cried Jerry, a new terror in his voice. "I heard Joe shriek!"

Slim, catching his meaning, snatched a rifle from beside one of the bodies, and with the butt of it began pounding frantically upon the side of the cave where the entrance had been.

There was no answering knock.

"Joe," shouted Jerry in a frenzied tone. "Joe! Can you hear me?"

No answer came, either from Joe or Frank.

"Pinned under tons of that stuff," gasped Slim, the words trembling upon his lips and a tear trickling down his cheek.

"I do not think so," the lieutenant assured them. "Both Joe and Frank were upon the outside when we entered."

"But they would try to get us out," said Jerry. "If they were out there they would give us some sort of signal that they were trying to help us."

"We might not be able to hear them," answered the lieutenant, even against his own judgment. "But look at it this way. Even though they never were inside here, they had a fair idea of what the place was like. They knew from that that we needed help, and needed it quickly. If one went alone, and anything happened to him on the way, the other might wait here indefinitely, not knowing whether he had got assistance or not. By going together they took the safest course."

And Lieutenant Mackinson's reasoning was correct. That was exactly the way Joe and Frank had figured it out, and, the latter forgetting all about his own wound, they had started as fast as they could for the American front.

"Keep cool, conserve your energy, and I feel certain everything will be all right," the lieutenant told the two friends with whom, in such a short time, he already had gone through so many harrowing experiences.

At that very same moment, a quarter of a mile away, Joe brought his companion to a halt, took out his flashlight, and, facing the American line, began making and breaking the connection in a way to give a number of short, even flashes.

Presently a light appeared, was extinguished and appeared again, at the edge of the American-French lines.

Joe had resorted to another sort of wireless—the "blinker"—and, not knowing the call signal for the station he was nearest, had given the prescribed call in such a case, a series of short flashes, or dots. The station had acknowledged, and he began sending his message out of the little battery in his hand:

"Americans. Three of party caught in cave-in. Need help."

And the answer was flashed back in the same code:

"Approach. Keep light on. Countersign."

Following these instructions, with Joe in the lead with the flashlight held out in front of him, they dashed on to the trenches. They gasped out the countersign, and were escorted by a sentry to the quarters of the officer of that particular section.

In a few words they told him what had happened.

Without an instant's delay the latter, a colonel of artillery, reached for his telephone.

"Ask Captain Hallowell to come here immediately," he said, and severed the connection.

He seemed already to have decided upon some sort of a plan, and his decisive manner gave the two lads a feeling of confidence in him. He reached into a drawer of his desk and drew out a large map. He ran his fingers across it and then came to a stop at a little black dot which appeared just in the angle of two converging red lines.

"Is that it?" he asked, turning to Jerry and Frank.

They examined the map carefully for a moment and then told him that it was.

Just then Captain Hallowell entered. His boots were spattered with mud, his face was grimy, and his eyes were bloodshot, indicating that he had been for many hours without sleep.

"Captain," said the colonel bluntly, "these young men are of the Signal Corps, as you you can see. They were detailed to-night to establish an outpost wire communication to Hill No. 8. You know it?"

"Very well, sir," the captain replied, his interest increasing.

"Well," continued the colonel, "they got there all right. But the other three in the party had hardly entered that hole when the entrance caved in."

"Great Scott!" ejaculated the captain. "I know that cavern. They can't last there long."

"Exactly," affirmed the colonel. "What is your suggestion?"

For a full moment Captain Hallowell was silent. "There is only one way," he said finally, "and that is a dangerous way. Blast them out."

"Blast them out?" repeated the colonel, but apparently without surprise. "How?"

"It would take too long to dig them out," Captain Hallowell answered. "And, besides, that could hardly be done without some sort of light, and that would attract enemy fire. There is but one chance, and that is to blast them out with one of our big guns!"

"Can you do it?" the colonel demanded again, in his blunt, insistent way.

"I will do my utmost to save them, sir," Captain Hallowell replied.

"Very well, then," answered his superior officer. "If you feel certain that is the only way, go ahead. Personally, knowing the place as I do, I see no other method myself. Have you the range?"

"I did have, sir," said Captain Hallowell, "but in such a delicate matter as this it would be necessary to be absolutely accurate. We have been firing practically all day, and the position of the guns changes slightly, of course. I would want to find a new and exact range."

He had noticed Frank's limp arm, and he turned to Joe.

"Take this flashlight," he ordered. "It is more powerful than yours. Get back there as quickly as you can, and follow to the letter these directions: Keep between us and that hill until you get to it. Stay on this side of the hill and crawl around toward the entrance until you get to a point where you can place this light, facing us, two feet above the ground and one foot in from the outer surface extremity. Leave it there until you see three quick successive rockets go straight up in the air from here. After that I will give you three minutes in which to get back to a place of safety. I'll put that flashlight out of business, and I think I can liberate your friends."

"Is your injury a serious one?" the colonel demanded of Frank.

"Very slight, sir. Only a flesh wound," Frank responded eagerly.

"Then take this light," the colonel ordered, "and follow him at a distance of a hundred yards. If anything should happen to your friend, you follow the directions you have just heard."

"Yes, sir," the lads responded in unison, and, with a hasty salute, were off.

Three times did Joe drop to the ground, as a shadow seemed to move somewhere out in the distance before him. But each time he was up and off again almost upon the instant, thinking of his own safety only as that of his three friends depended upon it.

And what of those inside?

Even the courageous Lieutenant Mackinson was beginning to show the anxiety he felt, while Jerry and Slim, despite their bravest efforts, gave way to occasional expressions of the horror of the thing.

They had pounded upon the walls until they had been overcome with despair, and then they had set to work digging with the only instruments at hand—the bayonets on the German rifles.

But soon they realized that this, too, was as hopeless as the pounding, for it further exhausted the energy which the foul air was rapidly sapping, without making any apparent opening in the thick earthen wall that surrounded them.

"Well," said Slim at last, gulping back his nausea, and smiling almost in his old time way, "I'm as anxious as anybody to keep up hope to the last. But if this is to be our end, I guess we can face it as Americans should."

"Bravo!" exclaimed Lieutenant Mackinson, "I always knew that each one of you fellows had the right sort of stuff in you."

And Jerry, too, slapped him affectionately on the back.

"Slim," he said, smiling over at his chum, and ready for his pun, even under such circumstances, "my head is feeling a 'trifle heavy,' but I'm game to stand up to the last."

Thus they sat down to wait—for just what, they did not know—while at that very moment, four feet away from them on the other side of the wall, faithful Joe was setting up the flashlight exactly according to directions.

For a few seconds he waited, and then, three times in quick succession, a rocket went into the air from just behind the American lines.

Over there Captain Hallowell himself found the range, submitted it to his most expert gunner, who verified it, and then they waited for the three minutes to elapse, during which Joe was to seek a place of safety.

It was in that interval, too, that Fate intervened for those within the cave, for they were sitting with their backs to the very point against which the shell was to be directed.

"We need all our strength," Lieutenant Mackinson was saying. "So long as possible we want to remain in full possession of our senses. The air is purer near the floor. I think it would be better to lie down."

And following his suggestion and example, the other two stretched themselves out in the middle of the cavern.

Within the American lines, at that point where a regiment of heavy artillery was stationed, Captain Hallowell raised his hand in signal to his gunner. Out on the parapet of the front trench an anxious colonel was standing, regardless of all danger, a pair of powerful glasses to his eyes. His vision was focused upon a little light far out in No Man's Land.

Two hundred feet away from that light Joe and Frank Hoskins lay prone upon the ground, silent, impatient, fearful, hoping.

With a quick motion the artillery captain swung his outstretched arm downward. There was a roar, a flash, and a great shell tore through the air. Out in No Man's Land there was a second explosion as the shell hit, and the target—a flashlight—was blown to atoms.

Over in the German trenches a sentinel chuckled at the thought of another wasted American shell, but out of the hole that that shell had torn three pale, haggard, and exhausted youths were crawling to safety and God's fresh air. And across No Man's Land dashed two pals to greet them.

American determination and American marksmanship had saved three American lives. The German sentinel might have his laugh if he liked.

It was hours later before the three who had been imprisoned learned how their rescue had been effected; but they got an inkling of it as they came within four hundred yards of the American-French front.

"What are you doing?" Lieutenant Mackinson had asked, as Joe brought the party to a stop.

"Just a moment and you will see," Joe had responded.

And, first in wonder and then with a dawning understanding, the other three read off his flashed message:

"Signal Corps men, and whole party safe."