aiting your orders at the field, Doctor."

"Good. I'll go up to the office of the Chief of Air Service and get in
touch with the pilot over the Chief's private line. There are some
orders that I wish to give him and some signals to be arranged."

* * * * *

Dr. Bird returned in a few minutes.

"The plane is taking off now and will be over the city soon," he
announced. "We'll take a stroll down the Avenue until we are in the
vicinity of the house, and then wait for the plane. Carnes will take
five of your men and go down behind the house and the rest of us will go
in front. Which building do you think it is, Bolton?"

"About the fourth from the corner."

"All right, the men going down the back will take station behind the
house next to the corner and the rest of us will get in front of the
same building. When the plane comes over, watch it. If you receive no
signal, go to the next house and wait for him to make a loop and come
over you again. Continue this until the pilot throws a white parachute
over. That is the signal that we are covering the right house. When you
get that signal, Carnes, leave two men outside and break in with the
other three. Get that apparatus on the roof and the men who are
operating it. Bolton and I will attack the front door at the same time.
Does everybody understand?"

Murmurs of assent came from the detail.

"All right, let's go. Carnes, lead out with your men and go half a block
ahead so that the two parties will arrive in position at about the same
time."

* * * * *

Carnes left the building with five of the operatives. Dr. Bird and
Bolton waited for a few minutes and then started down Pennsylvania
Avenue, the five men of their squad following at intervals. For
three-quarters of a mile they sauntered down the street.

"This should be it, Doctor," said Bolton.

"I think so, and here comes our plane."

They watched the swift scout plane from Langley Field swing down low
over the house and then swoop up into the sky again without making a
signal. The party walked down the street one house and paused. Again the
plane swept over them without sign. As they stopped in front of the next
house a white parachute flew from the cockpit of the plane and the
aircraft, its mission accomplished, veered off to the south toward its
hangar.

"This is the place," cried Bolton. "Haggerty and Johnson, you two cover
the street. Bemis,