Oh my god, Doctor Stockstill thought. This man, I do recognize him. This is Pruno Bluthgeld, the physicist. And he is right; a lot of people both here and in the East would like to get their hands on him because of his miscalculation back in 1972. Because of the terrible fall-out from the high-altitude blast which wasn’t supposed to hurt anyone; Bluthgeld’s figures proved it in advance.

“Do you want me to know who you are?” Doctor Stockstill asked. “Or shall we accept you simply as ‘Mr. Tree’? It’s up to you; either way is satisfactory to me.”

“Let’s simply get on,” Mr. Tree grated.

“All right.” Doctor Stockstill made himself comfortable, scratched with his pen against the paper on his clipboard. “Go ahead.”

“Does an inability to board an ordinary bus—you know, with perhaps a dozen persons unfamiliar to you—signify anything?” Mr. Tree watched him intently.

“It might,” Stockstill said.

“I feel they’re staring at me.”

“For any particular reason?”

“Because,” Mr. Tree said, “of the disfiguration of my face.”

Without an overt motion, Doctor Stockstill managed to glance up and scrutinize his patient. He saw this middleaged man, heavy-set, with black hair, the stubble of a beard dark against his unusually white skin. He saw circles of fatigue and tension beneath the man’s eyes, and the expression in the eyes, the despair. The physicist had bad skin and he needed a haircut, and his entire face was marred by the worry within him… but there was no “disfiguration.” Except for the strain visible there, it was an ordinary face; it would not have attracted notice in a group.

“Do you see the blotches?” Mr. Tree said hoarsely. He pointed at his cheeks, his jaw. “The ugly marks that set me apart from everybody?”

“No,” Stockstill said, taking a chance and speaking directly.