pairing 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."

The three men nearly tumbled over each other to get through the doorway
into the bitter cold outside. As they emerged from the cabin the gaze of
the guide swept the surrounding hills.

"There he goes!" he cried.

"Get him!" said Carnes sharply.

Walter ran forward a few feet and dropped prone on the ground, cuddling
the stock of his rifle to his cheek. Two hundred yards ahead a figure
was scurrying over the rocks away from the cabin. Walter drew in his
breath and his hand suddenly grew steady as his keen gray eyes peered
through the sights. Carnes and the doctor held their breath in
sympathy.

* * * * *

Suddenly the rifle spoke, and the fleeing man threw up his arms and fell
forward on his face.

"Got him," said Walter laconically.

"Go bring the body in, Carnes," exclaimed the doctor. "I'll take care of
the chap inside."

"Did you get him?" asked the voice eagerly, as the doctor stepped
inside.

"He's dead all right," replied the doctor grimly. "Who the devil are
you, and what are you doing here?"

"There is a light switch on the left of the door as you come in," was
the reply.

Dr. Bird found the switch and snapped on a light. He turned toward the
corner from whence the voice had come and recoiled in horror. Propped in
the corner was the body of a middle-aged man, daubed and spla