 What ultimately brings Torp down?
His task now was to bring a native, intact if possible, back to the carefully buried space cruiser where his two fellows and himself would drain the creature's mentality of all its knowledge. This latest planet, however, 72-P-3 on the chart, appeared to be an ideal world in every respect. An hour later, his scars and altered cartilage already healed and painless, Thig again scraped sand over the entrance to the space ship and set out along the moonlit beach toward the nearest path running inland to his home. Men had no mates on Ortha, sex had been overthrown with all the other primitive impulses of barbarism; so he was incapable of understanding the emotions that swept through his acquired memory.
 Thip shoots him with a blaster before he can comprehend what happened.
 He went mad from the same disease that's afflicting Thip.  Thip shoots him with a blaster before he can comprehend what happened.  His own madness. His overly trained mind can't handle the new circumstances.  He was never trained for a situation like this. He's not able to keep up with Thip.