important enough to tell Captain Strong
about. Working on the _Polaris_ twelve hours a day and staying up all
night to watch those two jokers has me all in."

Roger and Astro looked at each other and then silently nodded their
agreement.

"O.K.," said Tom, "we'll go to the skipper's hotel in Venusport and tell
him the whole thing. Let's see what he makes of it."

* * * * *

At that moment Captain Strong was in the office of Exposition
Commissioner Mike Hawks trying to make sense out of a series of reports
that had landed on the commissioner's desk. Hawks watched him carefully
as he studied the papers.

"You say this is the ninth report you've received since the fair opened,
Mike?" asked Strong finally.

Hawks nodded. He hadn't known whether to laugh off or seriously consider
the nine space skippers' reports that the sky over the exposition site
was dirty.

"Yes, Steve," he said. "That one came from the skipper of an express
freighter. He blasted off this morning and ran through this so-called
dirt. He thought it was just a freak of nature but reported it to be on
the safe side."

"I don't suppose he took a sample of the stuff?"

"No. But I'm taking care of that," replied Hawks. "There's a rocket
scout standing by right now. Want to come along?"

"Let me finish these reports first."

"Sure thing."

As Strong carefully checked each report, Commissioner Hawks rose and
began to stride restlessly back and forth across the spacious office. He
stopped in front of the window and stared out over the exposition
grounds, watching the thousands of holiday visitors streaming in and out
of the buildings, all unaware of the strange mystery in the sky above
them. Hawks' attention was drawn to the giant solar beacon, a huge light
that flashed straight out into space, changing color every second and
sending out the message: "Quis separabit homo"--Who shall separate
mankind?

This beacon that at the beginning of the exposition had reached into the
black void of space like a clean bright ray was now cloudy and
murky--the result of the puzzling "dirty sky."

"All right, Mike," Strong announced suddenly. "Let's go."

"Get anything more out of those reports?" asked Hawks, turning back to
his desk.

"No," replied the Solar Guard officer. "They all tell the same story.
Right after blast-off, the ships ran into a dirty sky."

"Sounds kind of crazy, doesn't it?"

"Crazy enough to check."