"I don't know," he said. "Not since the children almost killed me when they were four; you should have heard Donel shouting when he tore my respirator away by accident--he was playing with me, Sally--and saw me flop like a fish for air I could breathe, and saw my blood when another one touched my throat. I got away from them that time, but I never dared go back in after they searched out the camera lenses and smashed them. They _knew_, then--they knew we were in here, and they knew we didn't belong on their world." _And Falconer's kind would have gassed them, or simply re-mixed their air ... they would have, after a while, no matter what.... I know how many times I almost did...._ There was a new sound echoing through the dome. "Now they don't need us to let them out, anymore." There was a quick, sharp, deep hammering from outside--mechanical, purposeful, tireless. "That ... that may be Donel now."