sidered what was best to do. Of course he could have placed
Morones under arrest; could still do it; but that would not solve the
mystery of the two deaths and the missing 'lucene. If the choleric
factor was really guilty of the crimes, it would be better to let him
go his way in the hope that he would betray himself. Olear regretted
that he had not kept his tongue under closer curb. But there was no
use regretting. Perhaps, after all, he ought to turn back to pump
Morones for some helpful information.

* * * * *

His mind made up, he descended again until he was hovering a few feet
from the ground.

"Morones!" he called. "Morones!" He held the hatch open.

Morones came to the door of the residence. He had a tube in his hand,
a long-range weapon.

"Morones," Olear declared pompously. "I place you under arrest!"

The effect was instantaneous. Morones lifted the tube, and a
glimmering, iridescent beam sprang out. The ship was up and away in a
second, lurching and shivering uncomfortably every time the beam
struck it in its upward flight. A good few seconds continued
impingement....

But a miss is as good as a light-year. Miles high, Olear looked into
his telens. Morones had laid aside his tube and was working with an
instrument like a twin transit. Plotting the ship's course, naturally.
Olear set his course for the Earth, and kept on it for a good
twenty-four hours. Morones, if he was still watching him, would think
he'd gone back for reinforcements. Such an assumption would be
incredible now, but that was before the I. F. P. had achieved its
present tremendous reputation.

Beyond observation range, Olear curved back toward Mercury again, and
was almost inside its atmosphere when he made a discovery that caused
him to lose for a moment his natural indifference, and to clamp his
jaws in anger. The current oxygen tank became empty, and when he
removed it from the rack and put in a new one he found someone had let
out all of this essential gas. The valve of every one of the spare
tanks had been opened. Had Olear actually continued on his way to
Earth he would have perished miserably of suffocation long before he
could have returned to the Mercurian atmosphere. The officer whistled
tunelessly through his teeth as he considered this fact.

The visibility was by this time normal; that is, so poor it would have
been possible to land very close to the trading station. Olear was
taking no