"What?"
"It's all around us. You go through it to get here, but you can't stay anywhere but a few places like this."
"How do you know all of these things, Phil?"
"Oh, we know, all right. We had to find out."
"You must have ion counters," he said in what he hoped was a casual tone.
"We have lots of things."
Craig was thoughtful for a minute. The boy was obviously on his guard now.
"Those empty buildings?" Craig asked tentatively.
"They built them too close," said the boy. It seemed to be a safe subject. "They built them up as close as they thought was safe. Space is very valuable here. But they built them too close."
"Yet the 'we' you speak of live even closer?"