Swooping, rising, falling like a falcon in swift search of quarry, the
last plane of the Azores squadron swept in toward the on-rushing Eagle
of the Sky.

Undismayed by the swift, inexplicable fall of all its companions, it
still thrust on for the attack. In a few minutes it had come off the
port bows of the giant air-liner, no more than half a mile distant.
Now the watchers saw it, slipping through some tenuous higher
cloud-banks that had begun to gather, a lean, swift, wasplike
speedster: one of the Air Control Board's--the A.C.B.'s--most rapid
aerial police planes. The binoculars of the Master and Bohannan drew
the machine almost to fingers' touch.

"Only one man aboard her, with a machine-gun," commented the Master,
eyes at glass, as he watched the flick of sunlight on the attacker's
fuselage, the dip and glitter of her varnished wings, the blur of her
propellers. Already the roaring of her exhaust gusted down to them.

"Ah, see? She's turning, now. Banking around! We may catch a burst of
machine-gun fire, in a minute. Or, no--she's coming up on our tail,
Major. I think she's going to try and board us!"

"You going to let her?" protestingly demanded Bohannan. His hand
twitched against the butt of the Lewis. "In two seconds I could sight
an aft gun, sir, and blow that machine Hell-for-leather!"

"No, no--let that fellow come aboard, if he wants," the Master
commanded. And with eager curiosity in his dark eyes, with vast wonder
what manner of human this might be who--all alone after having seen