"Get up!" the voice commanded. Horning obeyed. "Now sit down on that lounge in front of you, with your hands on the arms." Horning crossed to the divan and turned around. For the first time, he faced his captor. It was the same man Horning had seen on the screen. He stood poised, cat-footed, back against the gleaming metaloid wall. An ugly, snub-nosed pistol of strange design was in his hand. And his face was Horning's face. Horning went rigid--shocked, half unbelieving. "Down!" rapped his counterpart. Horning sank numbly to the seat. "Who are you? Why did you come here?" Some of the numbness left Horning. Cold anger came in its place. "Why ask me?" he lashed back. "I thought you knew all the answers." The man's knuckles whitened on the pistol. "I want the truth!" Horning laughed. Of a sudden he felt bold and reckless. "I told you the first time. I came from another world, a different plane--" The gun moved in a flat, incisive gesture. "I know all that! The parallel worlds, the Worlds of 'If'. Parmenides and his theory of the Eternal Now. The idea that life's a book with an infinity of pages; that every event automatically creates coexisting planes, one for each possible outcome--" Horning's captor broke off. "But _why_? What drove you to cross the barrier?" Horning shrugged. "It was Myrtle--" he began wryly. The other started; fell back a step. "_Myrtle--?_" "My wife. I wanted to leave her." "You mean--you breached the continuum for no better reason...?" Horning laughed curtly. "For my part, I found it a very adequate reason." For a long moment the other stared at him. Then, abruptly, he, too, laughed. The snub-nosed gun's muzzle lowered. "You amaze me," his captor chuckled. He bowed. "Permit me to introduce myself. I'm Doctor Raymond X. Horning." "My coexisting counterpart on this plane--?" "Of course. The alter ego is bound to serve as a focal point when you cross the barrier." The man pocketed his gun and walked over to the table. "Let me mix you a drink. After such an experience, you need a pickup." * * * * * Horning leaned back, studying the other obliquely and trying to fathom the sudden change in his attitude. Too, he still marveled at the similarity between them. They were so alike they could pass as twins, he decided. Identical twins. The only difference between them lay in details of expression--the sardonic twist to the other's mouth; the chill, penetrating gleam in the deep-set eyes. His counterpart handed him a glass. "You amuse me, my friend. But I'm afraid you don't realize the full implications of what you've done." "Such as--?" Horning queried, sipping at the drink and finding it good. "Such as the fact that interdimensional transit is not only a logical impossibility, but a very practical menace." Horning frowned. "Why?"