"Come!" was the command borne to their ears in the faintest of whispers from the person leading the way.
Unhesitatingly the lads advanced. Jack had taken but a couple of steps before he collided with some solid object. The shock of contact brought forth a grunt of surprise. At the same moment Harry went through a similar experience. Ned met no resistance and nearly lost his hold of the others before he recovered his balance.
"Gee!" Jack whispered, "I've hit a wall!"
"Here, too!" put in Harry, lowering his whisper to a mere breath.
"Single file, lock step," directed Ned.
Jack and Harry fell in behind their Scout Master obediently, and the little party began groping its way along. Ned reached out a hand on either side as he went forward. His hands came in contact with walls that appeared to be made of stone. The dampness had gathered in great drops on the surface. A slime had been deposited that made Ned shudder as he felt it. He knew, however, that this was no time to permit an interruption through squeamishness.
There was now no guiding light in advance, and the boys cautiously picked their way along the stones, with Ned feeling every inch of the way before he set his foot down. Directly the lad heard another warning hiss. This time the sound was closer than formerly.
"Put your hand on my shoulder," came the whispered command.
Ned followed this instruction immediately. He judged by the height to which he raised his hand to rest it upon the other's shoulder that the stranger was a person of about his own build. His sense of touch also told him that the other's clothing was of a material similar to the khaki uniform he himself was wearing. A faint odor of gasoline and grease assailed his nostrils, particularly distinguishable because of the damp air in which the party was traveling.
Suddenly the boys were startled by the sound of an explosion that came faintly to their ears. The earth in their vicinity trembled.