seemed to come from nowhere.
He turned another knob, watched the marching, playing, whirling of
somnolent colors on the domed ceiling of his room.

At last he gave it up. Some sixth sense had him all jumpy. It was not
usual for Sime Hemingway to be jumpy. He was one of the coolest heads
in the I. F. P., the Interplanetary Flying Police who patrolled the
lonely reaches of space and brought man's law to the outermost orbit
of the far-flung solar system.

Now he jumped out of bed and examined the fastening of his door, the
door to the hotel corridor. There was only one, and it was secure.
Windows there were none, and investigation showed that the small ports
were all covered with their pivoted safety plates. He extinguished the
light, swung aside one of the plates, and peered out into the Martian
night. It was moonlight--both Deimos and Phobos were racing across the
blue-black sky. The waters of Crystal Canal stretched out before him,
seemingly illimitable. Sime knew that the distance to the other side
was twenty miles or more. Clear-cut through the thin atmosphere of
Mars, he could see the jeweled lights of South Tarog, on the other
side.

* * * * *

The hotel grounds, too, were well lighted. Long, luminous tubes, part
of the architecture of the buildings, aided the moons, shedding their
serene glow on the gentle slope of the red lawns and terraces, the
geometrically trimmed shrubs and trees. They were reflected warmly in
the dancing waves of the canal, though Sime knew that even in this,
the height of the summer season, the outside temperature was very near
freezing.

Now a hotel guard came along. He carried at his belt a neuro-pistol, a
deadly weapon whose beam would destroy the nervous structure of any
living creature. He went past the port with measured stride, and Sime
slid back the safety plate with a puzzled frown.

Why was he so nervous? This wasn't the first dangerous mission on
which he had embarked in the course of his official duty. And danger
was the element that gave zest to his life.

[Illustration: Clinging like leeches to the wall, the two men resisted
the warped gravitational drag.]

He began a methodical examination of his room, peering under the bed,
into closets, a wardrobe. Yet there was no sign of danger. Carefully
he inspected his bed for signs of the deadly black mold from Venus
that would, once it found lodgment in the pores of a man's skin,
inexorably in