had been taken, but whether there was any
significance in the thefts or not, no one knew.

There was a pattern in the thefts and robberies, nonetheless. They had
begun small and had increased. Scientific and technical
instruments--oscilloscopes, X-ray generators, radar equipment, maser
sets, dynostatic crystals, thermolight resonators, and so on--were
stolen complete or gutted for various parts. After a while, he had gone
on to bigger things--whole aircraft, with their crews, had vanished.

That he had not committed anywhere near all the crimes that had been
attributed to him was certain; that he _had_ committed a great many of
them was equally certain.

There was no doubt at all that his loot was being used to make
instruments and devices of unknown kinds. He had used several of them on
his raids. The one that could apparently phase out any electromagnetic
frequency up to about a hundred thousand megacycles--including
sixty-cycle power frequencies--was considered a particularly cute item.
So was the gadget that reduced the tensile strength of concrete to about
that of a good grade of marshmallow.

After he had been operating for a few years, there was no installation
on Earth that could be considered Nipe-proof for more than a few
minutes. He struck when and where he wanted and took whatever he needed.

It was manifestly impossible to guard against the Nipe, since no one
knew what sort of loot might strike his fancy next, and there was
therefore no way of knowing where or how he would hit next.

Nor could he ever be found after one of his raids. They were plotted and
followed through with diabolical accuracy and thoroughness. He struck,
looted, and vanished. And he wasn't seen again until his next strike.

Colonel Mannheim, who had carefully puffed a cigar alight and smoked it
thoughtfully during Stanton's recitation, dropped the remains of the
cigar into an ash receptacle. "Accurate but incomplete," he said
quietly. "You must have made some guesses. I'd like to hear them."

Stanton finished the last of his coffee and glanced at Dr. Farnsworth.
The biophysicist was thoughtfully looking down at his own cup, his
expression unreadable.

_All right_, Stanton thought, _he's looking for something. I'll let him
have both barrels and see if I hit the target_.

"I've thought about it," he admitted. He got up, went over to the coffee
urn, and refilled his cup. "I've got a pet theory of my own. It's just a
notion, rea