The truth dawned on him, then: The beam stopped short as if cut off by a wall ... because, indeed, a wall had risen up before it!

A dull, translucent wall of silvery grey.

Numbly, he lanced the beam skyward.

There, too, it broke on the grey shell.

Boone's panic channeled into fury. He spun about; struck savagely at the barrier.

Blood spurted from split knuckles. The wall remained.

Twisting, he hurled his full weight against the barrier.

Again, it threw him back.

He straightened, then; swung round the light-rod, searching the shell for some flaw, some weakness.

He found none.