pants of
ships and dirigible alike had been overcome by the deadly gas.

* * * * *

Dick banked, turned, leaned forward and shouted to Luke Evans, and,
when the old man turned his head, indicated to him to sweep the tarmac
with his ray.

The thread of black, broadening into a truncated cone, revealed
nothing save the luminous outlines of the buildings. Apparently the
tarmac was deserted. It was queer, too, that the silence of the night
before was gone. Dick shouted again, to assure himself of what he knew
already, and heard his own voice again.

Something had happened, something unexpected----or perhaps the crew of
the Invisible Emperor, satisfied with the effects of the deadly gas,
had not thought it necessary to go to any further trouble.

Suddenly Dick discovered that he was almost within the circle of the
line of magnetic force. Hurriedly he threw over the stick and kicked
rudder. It was not till he was again approaching the seashore that it
occurred to him that the force, too, was not in operation.

He opened throttle wide and shot seaward. He must ascertain what had
happened, and, if not too late, give warning without delay.

Then suddenly the vicious rattle of gunfire sounded in Dick's ears,
and, materializing out of the sky, came Von Kettler's face. Startled
for an instant, Dick quickly realized that it was Von Kettler in his
plane, with his hood thrown back.

And Dick realized that his own hood was thrown back. Two faces and
nothing else, were the whole visible setting for battle.

But that look upon Von Kettler's face was even more demoniacal than
before. Mad with rage at the prospective escape of his prey, and
infuriated by his half-sister's appearance in the plane, Von Kettler
had thrown all caution to the winds. In his insane hatred he was
prepared to shoot down Dick's plane and send Fredegonde to destruction
with it.

* * * * *

If Dick chose to replace his hood he would have the madman at his
mercy. And, if he had thought about it, he would have done so, with
Fredegonde sitting behind him. But the idea did not enter his mind.
Consumed with rage almost equal to Von Kettler's, he only saw there
the face of one of those who had inflicted an unspeakable outrage upon
the President of his country.

The memory of old Hargreaves, chained before the mock-Emperor's
throne, enraged Dick more than the holocaust of lives taken by the
assassi