A car moved rapidly through the streets of the city. At the wheel was a man dressed in a captain's uniform. The machine whirled onto the highway that led toward the factory. A barricade, lighted by torch-lanterns, barred his path. A sentry with a bayoneted gun stood to one side, signaling a halt.

The car slowed.

"Captain Ted Taylor, ordnance department!" the captain said, extending his pass toward the sentry.

The sentry signaled him on.

The car came within a stone's throw of the factory, where it turned into a parking lot. The officer climbed out, noiselessly, and moved into the shadows.

Once Captain Taylor had been a scientist, but that was long ago, before wars had made biology very unexciting.

Out of the shadows a second figure moved. He was a short, stocky man, compared with the slender, graceful figure of the captain.

"Ps-st! Captain!"

"Masters!"

"You got my short-wave call, I see. I was afraid you would be asleep. He came late, but he's in the tunnel now."