t answer. He went back to the squad ship and armed
himself. Patrolman Willis followed suit. The sergeant boobied the squad
ship so no unauthorized person could make use of it, and so it would
disable itself if anyone with expert knowledge tried. Therefore, nobody
with expert knowledge would try.

The two cops began a painstaking quest for police-type evidence to tell
them what had happened, and how and why the _Cerberus_ was missing,
after a clumsy but safe landing on Procyron III and when all sanity
demanded that it stay there, and when it was starkly impossible for it
to leave.

* * * * *

Sergeant Madden and Patrolman Willis were, self-evidently, the only
human beings on a planet some nine thousand miles in diameter. It was
easy to compute that the nearest other humans would be at least some
thousands of thousands of millions of miles away--so far away that
distance had no meaning. This planet was something over nine-tenth
rolling sea, but there were a few tens of thousands of square miles of
solid ground in the one archipelago that broke the ocean's surface. It
was such loneliness as very few people ever experience. But they did not
notice it. They were busy.

They went over the ground immediately about the landing place. Rocket
flame had splashed it, both at the _Cerberus'_ landing and at the
impossible take-off. There was nothing within a hundred yards not burned
to a crisp. They searched outside that area. Sergeant Madden rumbled to
his companion:

"Where'd the other ship land?"

Patrolman Willis blinked at him.

"There had to be another ship!" said Sergeant Madden irritably. "To
bring the extra rockets. The other ship had to've brought 'em. And it
had to have rockets of its own. There's no spaceport here!"

Patrolman Willis blinked again. Then he saw. The _Cerberus_ carried one
set of emergency-landing rockets, for use in a descent on a refuge
planet if the need arose. The need had arisen and the _Cerberus_ had
used them. Then, from somewhere, another set of rockets had been
produced for it to use in leaving. Those other rockets must have come on
another ship. But it was a trifle more complicated than that. The
_Cerberus_ had carried one set of rockets and used them. One. It had
been supplied with another set from somewhere. Two. They must have been
brought by a ship which also used a set of rockets to land by. That made
three. Then the other ship must have had a fourth s