provide a hostage."

"You talk in riddles."

"Perhaps, but I give you the answer. Operative Number Eighty-one will
come for me in a two-seater just at dark. But he will not be the one to
take me back."

"_Ach! Himmel!_"

"_Das ist ziemlich gescheit!_"

Count von Herzmann shrugged his shoulders at the exclamatory surprise
and compliment. "Clever? No. Merely an old custom borrowed from old
wars. Operative Number Eighty-one will be held at the headquarters at
Montfaucon--pending my return. If I do not return in five days, then he
too will hold the stage a brief minute before a firing wall. Then,
perhaps we will meet beyond the Great Line--where there are no wars or
rumors of wars. Is there anything else you have to take up with me now,
_Herr Hauptmann?_"

"Ach, yes! If you are successful, and return within your scheduled time,
how will this operative, held at Montfaucon, make a satisfactory
explanation to the Americans regarding his long absence?"

Count von Herzmann snapped his fingers. "Poof! That is secondary, and a
problem which I leave to the superior mind of _Herr Hauptmann_--and
the High Command."

CHAPTER XII

Wheels Within Wheels

1

Near noon, the following day, a motor cycle with side car snorted to a
sudden stop at the newly erected hangar tents of an American Pursuit
Group, and McGee crawled stiffly from the bone-racking, muscle-twisting
"bath tub." He thanked the mud-splashed, goggled driver, adding, by way
of left-handed compliment, that he had been given more thrills in the
last five kilometers than he had received in all his months in the
Allied Air Service.

He turned toward the hangar. There was but one ship on the field, a
two-seater. By its side stood Siddons and his air mechanic. They seemed
to be in close-headed conference.

McGee clicked his teeth in a little sound of suppressed emotion, slipped
through the hangar door and stood face to face with his own old Ack
Emma.

"For the luva Pete!" exclaimed the startled air mechanic. "When did you
get here, Lieutenant?"

McGee extended his hand in greeting. Williams grasped it, eagerly.

"Well, for the luva Pete?" he repeated, lacking words in his surprise
and pleasure. "Lieutenant Larkin! Oh, Lieutenant Larkin!" he began
roaring. "Oh, Bill! Where's Larkin?"

"Just left a minute ago," came a voice from under the hood of a new
Spad. "Went over to his quarters to wash up. Grease from head to foot."

"I'll go show you his qua