Something came out of Boulder Lake National Park.  All humans had supposedly fled from it.  It was abandoned to the creatures of the thing from the sky.  But something came out of it.

Nobody saw the thing, of course.  Nobody could approach it, which was the point immediately demonstrated.  No human being could endure being within seven miles of whatever it was.  It was evidently a vehicle of some sort, however, because it swung terror beams before it, and terror beams on either side, and when it was clear of the Park it played terror beams behind it, too.  Men who suffered the lightest touch of those sweeping beams of terror and anguish moved frantically to avoid having the experience again.  So when something moved out of the Park and sent wavering terror beams before it, men moved to one side or the other and gave it room.

On a large-scale map in the military area command post, its progress could be watched as it was reported.  The reports described a development of unbearable beam strength which showed up as a bulge in the cordon’s roughly circular line.  That bulge, which was the cordon itself moving back, moved outward and became a half-circle some miles across.  It continued to move outward, and on the map it appeared like a pseudopod extruded by an enormous amoeba.  It was the area of effectiveness of a weapon previously unknown on earth—­the area where humans could not stay.

Deliberately, the unseen moving thing severed itself from the similar and larger weapon field which was its birthplace and its home.  It moved with great deliberation toward the small town of Maplewood, twenty miles from the border of the Park.

Jeeps and motorcycles scurried ahead of it, just out of reach of its beams.  They made sure that houses and farms and all inhabited places were emptied of people before the moving terror beams could engulf them.  They went into the town of Maplewood itself and frantically made sure that nothing alive remained in it.  They went on to clear the countryside beyond.

The unseen thing from the Park moved onward.  High overhead there was a dull muttering like faraway thunder, but it was planes with filled bomb racks circling above the starlit land.  There were men in those planes who ached to dive down and destroy this separated fraction of an invasion.  But there were firm orders from the Pentagon.  So long as the invaders killed nobody, they were not to be attacked.  There was reason for the order in the desire of the government to be on friendly terms with a race which could travel between the stars.  But there was an even more urgent reason.  The aliens had not yet begun to murder, but it was suspected that they had a horrifying power to kill.  So it was firmly commanded that no bomb or missile or bullet was to be used unless the invaders invited hostilities by killing humans.  Their captives—­the crew of a helicopter—­might be freed if aliens and men achieved friendship.  So for now—­no provocation!