As they reached the door they were aware of a struggle which was going on inside. With an oath the doctor threw his massive frame against the door. It creaked, but the solid oak of which it was composed was proof against the attack, and he drew back for another onslaught. From the house came a pistol shot, followed by a despairing cry and a guttural shout. Reinforced by Carnes, the doctor threw his weight against the door again. With a rending crash it gave, and they fell sprawling into the cabin. The doctor was the first one on his feet.
“Who are you?” asked a voice from one corner. The doctor whirled like a flash and covered the speaker with his pistol.
“Put them up!” he said tersely.
“I am unarmed,” the voice replied. “Who are you?”
“We’re from the United States Secret Service,” replied Carnes who had gained his feet. “The game is up for you, and you’d better realize it.”
“Secret Service! Thank God!” cried the voice. “Get Koskoff––he has the plans. He has gone out through the tunnel!”
“Where is it?” demanded Carnes.
“The entrance is that iron plate on the floor.”
Carnes and the doctor jumped at the plate and tried to lift it, without result. There was no handle or projection on which they could take hold.
“Not that way,” cried the voice. “That cover is fastened on the inside. Go outside the building; he’ll come out about two hundred yards north. Shoot him as he appears or he’ll get away.”