is! Give it a
shot, Gregg!"

Snap was unarmed, but he flung his hands out menacingly. The figure,
which may perhaps not have been aware of our city safeguard, was taken
wholly by surprise. A human figure. Seven feet tall, at the least, and
therefore, I judged, doubtless a Martian man. The black cloak covered
his head. He took a step toward us, hesitated, and then turned in
confusion.

Snap's shrill voice was bringing help. The whine of a street guard's
alarm whistle nearby sounded. The figure was making off! My pencil-ray
was in my hand and I pressed its switch. The tiny heat-ray stabbed
through the glare, but I missed. The figure stumbled, but did not fall.
I saw a bare gray arm come from the cloak, flung up to maintain its
balance. Or perhaps my pencil-ray of heat had seared the arm. The
gray-skinned arm of a Martian.

Snap was shouting, "Give him another!" But the figure passed beyond the
actinic glare and vanished.

We were detained in the turmoil of the corridor for ten minutes or more
with official explanations. Then a message from Halsey released us. The
Martian who had been following us in his invisible cloak was never
caught.

We escaped from the crowd at last and made our way back to the
Planetara, where the passengers were already assembling for the outward
Martian voyage.

CHAPTER II

"_A Fleeting Glance_--"

I stood on the turret-balcony of the Planetara with Captain Carter and
Dr. Frank, the ship surgeon, watching the arriving passengers. It was
close to the zero hour: the level of the stage was a turmoil of
confusion. The escalators, with the last of the freight aboard, were
folded back. But the stage was jammed with the incoming passenger
baggage: the interplanetary customs and tax officials with their X-ray
and Zed-ray paraphernalia and the passengers themselves, lined up for
the export inspection.

At this height, the city lights lay spread in a glare of blue and yellow
beneath us. The individual local planes came dropping like birds to our
stage. Thirty-eight passengers for this flight to Mars, but that
accursed desire of every friend and relative to speed the departing
voyager brought a hundred or more extra people to crowd our girders and
bring added difficulty to everybody.

Carter was too absorbed in his duties to stay with us long. But here in
the turret Dr. Frank and I found ourselves at the moment with nothing
much to do but watch.

"Think we'll get away on time, Gregg?"