"Miss Griffin, I--" But Cragin let the words trail off because he knew that for the first time in his life, he was out of his element. True, he was in an unknown Space on an unknown sphere, as he'd been too many times before to count--but this was somehow different. And Lin Griffin knew more answers than he did. He thought about showing her the small white rectangle of enamelite that Kirkholland had given him, but it would make him more the fool. She knew what he was; she had not defied his authority. She had not actually tried to evade him. She had simply talked him into something and he didn't know what it was. Believing her was his fault. He followed her about a quarter mile over the smooth metal plain until she stopped before a ragged mar that had been forcefully seared into its surface by a dis-torch. Cragin saw what it was; it was a cross. The girl paused a moment. He had never seen anyone bow their head to pray before. He stood silent. Finally all she said was, "Someday I'll make them tell me what they did with him." "All right. Let's get on with it. Where to now?" "Not far." It was only a hundred yards further that they stopped; this time the sear in the hard metal was shapeless, not as deep as the one before and obviously more hastily made. She fumbled in the pocket of her suit, and by instinct, Cragin's hands fell lightly over the butts of his guns. She produced a small, circular thing, pushed a catch on its side, and placed it near the ragged burn. "A vibrokey," she said matter of factly. "Something father devised. You can find anything with it, once you know the object's vibration pattern. And you can open anything with it. It experiments with all possible combinations of magnitudes and speeds of vibrations, until it simply hits the particular pattern needed. Without it I would never have found the burns I left, and without it we wouldn't get in. Father said it could shake a whole building down...." Within seconds a panel less than a meter square slid back, and he and the girl were beneath it. Then it was closing. There was a passageway of some sort with a totally invisible source of illumination. Almost like what he'd run across beneath the abandoned gold mines on Venus, except.... "Now we have to move quickly," Lin interrupted his thoughts. "We have very little time. They know we're here." "I didn't hear--" * * * * * "They know. Down this way." There was another burn, this time on the wall of the long, gently twisting tube. It hurt his eyes; it was like walking down a huge, brightly-polished gun barrel, except that it was not quite straight, and it was hard to tell just when it turned. "Can you do what your father failed to do?" Cragin said. He asked only to hear his own voice; it gave him at least a finger-hold on reality. "Perhaps, if there is time. I did not waste those weeks in the hospital."