ed over the banks of the
spillway, the eyes of its pilot scouring the ground. It zoomed just in
time to miss the wall of the dam, banked, doubled like a scared
jack-rabbit, dove down again, coming within feet of the spillway
channel. Mad, inspired flying! But what good could it do?

Then from its cockpit came a yell.

"There! There! By heaven, I can make it!"

Two or three hundred feet--it was not clear just how far--from the
face of the dam, on the bare right bank of the channel, a tiny
pin-prick of black was moving slowly along. It seemed to move by
itself through the air. And now, as the screaming plane banked again
and came rushing closer, the pin-prick grew into a black box that
suddenly stopped its advance, held motionless some four feet off the
ground. Though the man who held it was not visible, Chris could fancy
him staring up at the plane, could fancy the look of consternation on
his unseen face.

Two hundred feet was the range of the rays! Was Kashtanov that close?
Obviously the controls had not yet been set, for he still held the
box. But he could switch them on in a second and fling the deadly
machine up toward the dam, if he were at present just out of range. A
second--a second!

"Damn you, here goes!" roared Chris.

He wrenched the stick way over. The plane appeared to hang crazily on
one wing. Then it leveled off and stuck its nose down, flipping its
tail up, and down--down--down it bellowed; with no hope in the world
of ever coming out of its insane plunge.

What he saw in that last momentary glimpse was burned forever into
Chris Travers' memory. There was the black box, hanging in the air
straight before the plane's thundering nose; there, behind it, the
black tide of the spillway waters; and, still further behind, he could
see the other bank and the hydro-electric station, and a few tiny
figures that rushed out from it just then to see what some fool flyer
was doing.

All this flashed into his sight, etched against the sable night as if
in flame. Then the plane's snout smashed into the black box hanging
before it, and the propeller crunched through a naked, invisible body.
A ragged scream that marked the passing of Kashtanov split through the
air for a flash of time, and the dark, blurred mass that was an
airplane teetered clean over and flopped into the rushing spillway
channel.

* * * * *

The men who had scrambled out from the hydro-electric station stare