"Right," replied Hal. "Let's get busy."

"How are we to get the aeroplane out of the shop? You know the door
is locked."

"Yes, but I know something else, too. I noticed it to-day, and wondered
why those men who came after the key didn't take advantage of it."

"What is it?"

"The bolts in the hinges of the door can be lifted out easily, and we can
take the doors off."

"But we must get rid of the two soldiers who keep guard at night."

"We will do that some way, all right."

"Come on, then; let's get started."

Chester opened the door of their room and peered out.

"Coast clear," he announced.

Softly the two boys stole from the room and crept along the hall. They
tip-toed down the stairs, opened the door, and went out with scarcely a
sound. Outside they stopped. In front of the workshop they could see the
two guards in conversation.

"We must get to the rear of the shop without being seen," whispered
Hal. "When one guard makes his rounds, we must grab him and prevent him
from making an outcry. We can then dispose of the other. You wait here
a minute, while I go back and get a piece of clothes-line, so we can
tie them up."

He returned almost immediately with two pieces of rope.

"Careful, now," whispered Hal, as, keeping in the shadow of the house,
they made a short detour.

Out of sight of the guards, they made a silent dash for the rear of the
workshop, where they stood, silently awaiting the approach of the guard.

"I hate to do this," whispered Hal, as he heard the footsteps of the
guard; "but it has to be done."

As the guard rounded the corner of the shop, Hal struck out. Swift and
true was the blow; and struck upon the point of the chin, the man
crumpled up without a sound.

The boys bound and gagged him quickly, using their handkerchiefs to stuff
into his mouth. Then silently they ran to the opposite side of the shop
and waited the approach of the second guard.

A moment later his footsteps were heard approaching. As he turned the
corner, Hal again struck out swift and true, and the second man went to
the ground. The boys bound and gagged him, and then hastened to the front
of the shop.

As Hal had predicted, the doors were removed with little difficulty, and
silently the lads rolled the huge machine into the open. Hal's experience
with automobiles had taught him something of engines, so he had little
trouble starting this one. Finding everything in working order, Hal
climbed into the