e a grenade. There's a string tied to it. At a guess,
that sandy-haired guy set it up like that saboteur sergeant down in
Brazil. Only--it rolled a little. And this one goes off when the wheels
go down. I think, too, if we belly-land----Better go around again, huh?"

The pilot nodded. "First," he said evenly, "we get word down to the
ground about the sandy-haired guy, so they'll get him regardless."

He picked up the microphone hanging above and behind him and began to
speak coldly into it. The transport plane started to swing in wide,
sweeping circles over the desert beyond the airport while the pilot
explained that there was a grenade in the nose wheel well, set to
explode if the wheel were let down or, undoubtedly, if the ship came in
to a belly landing.

Joe found himself astonishingly unafraid. But he was filled with a
pounding rage. He hated the people who wanted to smash the pilot gyros
because they were essential to the Space Platform. He hated them more
completely than he had known he could hate anybody. He was so filled
with fury that it did not occur to him that in any crash or explosive
landing that would ruin the gyros, he would automatically be killed.

3

The pilot made an examination down the floor-plate hole, with a
flashlight to see by and two mirrors to show him the contents of a spot
he could not possibly reach with any instrument. Joe heard his report,
made to the ground by radio.

"It's a grenade," he said coldly. "It took time to fix it the way it is.
At a guess, the ship was booby-trapped at the time of its last overhaul.
But it was arranged that the booby trap had to be set, the trigger
cocked, by somebody doing something very simple at a different place and
later on. We've been flying with that grenade in the wheel well for two
weeks. But it was out of sight. Today, back at the airfield, a
sandy-haired man reached up and pulled a string he knew how to find.
That loosened a slipknot. The grenade rolled down to a new position. Now
when the wheel goes down the pin is pulled. You can figure things out
from that."

It was an excellent sabotage device. If a ship blew up two weeks after
overhaul, it would not be guessed that the bomb had been placed so long
before. Every search would be made for a recent opportunity for the
bomb's placing. A man who merely reached in and pulled a string that
armed the bomb and made it ready for firing would never be suspected.
There might be dozens of