"What is it?" Rafferty interrupted. In the sweltering steam of the Refuge he was gasping for breath; perspiration dripped from his reddening face.

"We want to leave here," a female piped.

"And we're walking," another announced, a male. "We've decided—you can't keep us shut up in here. We have rights."

For an interval Rafferty discussed the situation with them; then, abruptly, he turned and made his way back through the lock. "That's my limit," he murmured to Cussick, mopping his forehead. "I can tolerate three minutes in there, and then the ammonia goes to work."

"You're going to let them try it?" Cussick asked.

"Activate the Van," Rafferty said to his technicians. "Have it ready to pick them up as they drop." To Cussick he explained: "The Van is an iron lung for them. There won't be too much risk; they're fragile, but we'll be ready to gather them up before damage is done."

Not all the mutants were leaving the Refuge. Four hesitant figures were picking their way along the passage that led to the elevator. Behind them, their three companions remained in the safety of the entrance, huddled together in a group.

"Those three are more realistic," Doctor Rafferty said. "And older. The slightly heavier one, the dark-haired one who looks the most human, is Frank. It's the younger ones who give us the trouble. I'll put them through a gradational series of stages to acclimatize their overly-vulnerable systems—so they won't suffocate or die of heart stoppage." Worriedly, he went on: "What I want you to do is clear the streets. I don't want anybody to see them; it's late and there won't be many people out, but just in case..."