protection. They moved steadily, as if inviting the fate that had
overtaken others. The short wave reports from smashed trucks seemed
improbable to them, but the expedition was equipped to investigate
even such unlikely happenings.

The four cars in the lead contained five men each. Each man was armed
with a rifle containing a single cartridge in its chamber and none in
its magazine. The rifles pointed straight up. There was more
ammunition in the light truck behind, and it was in clips ready for
use, but the truck body was of iron. If that ammunition detonated, it
could do no harm. If it did not, it would be available for use against
the single man mentioned by the driver of the last truck to be
wrecked.

But Lockley saw them coming. They came sedately down a long straight
stretch of road. He climbed a rocky wall beside the highway to a
little ravine that led away from the road. He posted himself where he
was extremely unlikely to be seen. Then he waited.

The cavalcade of cars appeared. It drove briskly toward Lockley at
something like thirty miles an hour. Perhaps ten yards separated the
lead car from the second. The truck was a trifle closer to the four
man-carrying vehicles. They swept along, every man alert. They would
pass forty feet below Lockley.

He did nothing. His device was already turned on. He watched in
detached calm.

The lead car stopped as if it had run into a brick wall, while rifles
inside it blew holes in its top. The second car crashed into it,
rifles detonating. The third car. The fourth. The truck piled into the
others with a gigantic flare and furious report, each separate brass
cartridge case exploding in the same instant. The truck became scrap
iron.

Lockley went away along the small ravine. From now on he would avoid
the highway. He estimated that he would arrive at Boulder Lake itself
about half an hour after dark. It occurred to him that then Jill would
have been a prisoner of the invaders for something more than twelve
hours, at least ten of them at their headquarters.

Before he began the climb that would take him to the invaders, Lockley
stopped at a small stream.

He drank thirstily.

CHAPTER 10

There was a three-day-old moon in the sky when the last colors faded
in the west. When darkness fell it was already low. It gave little
light; not much more than the stars alone. It did help Lockley while
it lasted however. He knew the terrain about Boulder Lake but not