"It was a rat," Bart exclaimed wrathfully, as he nursed his wounded hand. "The beggar jumped straight at it. It feels as though he'd made his teeth meet through it"

Billy whipped out his handkerchief and was binding it around his comrade's hand, when a gray form sprang from the darkness and fastened its teeth in his trousers leg just grazing the skin. Frank made a kick at it, but as he did so, his foot slipped on the damp stone and the flashlight flew out of his hand, leaving them in utter darkness. He stooped to try to find it, but his hand touched a furry coat and he drew back just in time to escape a savage snap.

Then as if by magic those red pin points, that they now knew were eyes, seemed to spring up from every direction. There were rats everywhere, an army of them, rats ahead of them and rats behind them, gathering to oust these human intruders from their domain. Singly they were contemptible opponents, but now they had the strength that came from numbers, and they knew it.

And the Army Boys knew it too. For an instant panic gripped at their hearts. The next moment they had pulled themselves together.

"Back to the trap door, fellows!" said Frank tensely. "Fast, but not too fast. Don't run. And don't shoot, or we may hit each other. Draw your revolvers and club them off with the butts."

They retraced their steps as well as they could in the darkness. The rats knew that they were retreating, and they grew bolder. Again and again they fastened themselves on their arms and legs, and had to be beaten off with the revolver butts. All the boys were bitten many times, and it seemed to them that they would never come to the end of the passage alive. But none of their assailants reached their throats, although one had to be knocked from Billy's shoulder, and at last the nightmare journey ended when they stumbled against the steps that led to the trap door. Frantically they heaved the door up and clambered out and sank down on the ice covered ground, spent and out of breath and utterly exhausted.

CHAPTER XVIII

THE CRITICAL MOMENT

For a time the Army Boys sat there, panting and gasping from their unwonted exertions, yet filled with a deep thankfulness that they had won through as well as they had.

At length Frank gave a short laugh that had in it little trace of mirth.