"Had me this buddy in the Russian camp, Siberia, his thumb was frostbit. Medics came by and they cut it off. Month later he’s tossin’ all night. Elroy, I said, what’s eatin’ you? Goddam thumb’s itchin’, he says. So I told him, scratch it. McCoy, he says, it’s the other goddam thumb." When the construct laughed, it came through as something else, not laughter, but a stab of cold down Case’s spine. "Do me a favor, boy."