"It's—it's on Callisto...."
"Callisto—?" Dane stared. "That's Kalquoi territory, isn't it?"
"Yes, of course. They occupied it when they took over the outer planets thirty years ago."
"Then the shaft—"
"—is a relic of the days just before the occupation," Nelva finished for Dane. "It was a weapon, Clark—a weapon set up at Sandoz, the chief human city on Callisto. The Sandoz Shaft, they called it. Only then it didn't work, so people ended up saying it was the Sandoz Tombstone. It's mentioned in all the Kalquoi Invasion knowledge tapes. That's how I know about it."
Prickles of excitement ran up and down Dane's spine. For the first time he began to feel as if he were making progress, coming to grips with the mysteries which seemed ever to surround him.
"Do you know any more about the thing?" he demanded of Nelva. "How was it supposed to work? What went wrong?"
The girl's smooth brow furrowed in concentration. "As I recall, the shaft was nothing but a gigantic Udellian transmitter."
"A Udellian transmitter—?"