btained before. The blood sugar and protein
determinations fell into the pattern they had originally expected for a
creature of this type. Even more surprising, the level of the antibody
against the plague virus was high--far higher than it could have been
from the tiny amount that was injected into the creature.

"They must have been making it themselves," Dal said, "and our
inoculation was just the straw that broke the camel's back. All of those
people must have been on the brink of symptoms of the infection, and
all we did was add to the natural defenses they were already making."

"Then why did the symptoms appear?" Jack said. "If that's true, we
should have been _helping_ them, and look at them now!"

Tiger appeared at the door, scowling. "We've got real trouble, now," he
said. "I can't get through to a hospital ship. In fact, I can't get a
message out at all. These people are jamming our radios."

"But why?" Dal said.

"I don't know, but take a look outside there."

Through the viewscreen it seemed as though the whole field around the
ship had filled up with the crowd. The first reaction of terror now
seemed to have given way to blind fury; the people were shouting
angrily, waving their clenched fists at the ship as the spokesman tried
to hold them back.

Then there was a resounding crash from somewhere below, and the ship
lurched, throwing the doctors to the floor. They staggered to their feet
as another blow jolted the ship, and another.

"Let's get a screen up," Tiger shouted. "Jack, get the engines going.
They're trying to board us, and I don't think it'll be much fun if they
ever break in."

In the control room they threw the switches that activated a powerful
protective energy screen around the ship. It was a device that was
carried by all GPP Ships as a means of protection against physical
attack. When activated, an energy screen was virtually impregnable, but
it could only be used briefly; the power it required placed an enormous
drain on a ship's energy resources, and a year's nuclear fuel could be
consumed in a few hours.

Now the screen served its purpose. The ship steadied, still vibrating
from the last assault, and the noise from below ceased abruptly. But
when Jack threw the switches to start the engines, nothing happened at
all.

"Look at that!" he cried, staring at the motionless dials. "They're
jamming our electrical system somehow. I can't get any turn-over."

"Try it again," Tiger