"I've some faint hope of a few directions in that sealed-up metal case with the inscription on it. I'm going to take some tools and break into it. It's a gamble, but there's nothing to lose." He ate briskly, with a good appetite. Sandy was very silent. Pam said abruptly, "We saw that case. And I smelled fresh air there. Not pure air like here in the ship, but not dead air like the air everywhere else." "Near a power generator, Pam, there'd be some ozone," Holmes said patiently. "It makes a lot of difference." "It wasn't ozone," said Pam firmly. "It was fresh air. Not canned air. Fresh!" Holmes looked at Burke. "Did you or Keller find out how the air's refreshed here? Did anybody throw a switch for air apparatus?" Keller said mildly, "Apparatus, no. Air exchange, yes. I threw switches also for communication with base. Also emergency communication. Also dire emergency. Nothing happened." "You see, Pam?" said Holmes. "It was ozone that made the air smell fresh." Sandy was wholly silent until the meal was over. Then Holmes went moodily off with Keller, to use the cube-reading devices in the instrument-room and try to find, against all apparent probability, some clue or some communication which would enable something useful to be done. Holmes was trying hard to believe that things were not as bad as Burke announced, and not nearly so desperate that they had to try to find the descendants of a long-vanished civilization for a chance to offer resistance to the Enemy. Keller said confidentially, just before they reached the instrument-room, "Burke's an optimist." And at that moment, back in the little plastic spaceship, Burke was saying to Sandy, "You can come along if you like. There are a couple of things to be looked into. And if you want to come, Pam--" But Pam touched the papers Keller had given her and said reservedly, "I'll code and send this stuff. Go ahead, Sandy." Sandy rose. She followed Burke out of the ship. She was acutely aware that this was the first time since they had entered the ship that she and Burke could speak to each other when nobody could overhear. They'd spoken twice when the others were presumably asleep. But this was the first time they'd been alone. When they'd passed through the door with the rounded corners, they were completely isolated. Overhead, brilliant light-tubes reached a full mile down the gallery in one direction, and half as far in the other. The vast corridor contained nothing to make a sound but themselves. "It's this way," said Burke. Sandy knew the way as well as he did, or better, but she accepted his direction. Their footsteps echoed and reëchoed, so that they were accompanied by countless reflections of heel-clicks along with the normal rustling and whispering sounds of walking. They went a full quarter-mile from the ship-lock door, and came to a very large arched opening which gave entrance to a corridor slanting downward. "Supplies came up this ramp," said Sandy.