Communication was telepathic. Tennant could have yodeled or yelled or sung _Mississippi Mud_ and Opal would have shown no reaction. Yet Tennant suspected that the captors could hear somewhere along the auditory scale, just as perhaps they could smell, although not in any human sense. _You will approach without use of your appendages._ The command was as clear as if it had been spoken aloud. Tennant took a deep breath. He thought of the space beside Opal. It took about three seconds and he was there, having spanned a distance of some ninety feet. He was getting good at it. Dog does trick, he thought. * * * * * He went through the entire routine at Opal's bidding. When at last he was allowed to relax, he wondered, not for the first time, if he weren't mastering some of the alleged Guru arts. At once he felt probing investigation. Opal, like the rest of the captors, was as curious as a cat--or a human being. Tennant sat against a wall, drenched with sweat. There would be endless repetition before his workout was done. On Earth, dogs were said to be intellectually two-dimensional creatures. He wondered if they felt this helpless futility when their masters taught them to heel, to point, to retrieve. Some days later, the training routine was broken. He felt a sudden stir of near-sick excitement as he received the thought: _Now you are ready. We are going through at last._ Opal was nervous, so much so that he revealed more than he intended. Or perhaps that was his intent; Tennant could never be sure. They were going through to Tennant's own dimension. He wondered briefly just what his role was to be. He had little time to speculate before Opal seemed to envelop him. There was the blurring wrench of forced teleportation and they were in another room, a room which ended in a huge irregular passage that might have been the interior of a giant concertina--or an old-fashioned kodak. He stood before a kidney-shaped object over whose jagged surface colors played constantly. From Opal's thoughts it appeared to be some sort of ultradimensional television set, but to Tennant it was as incomprehensible as an oil painting to an animal. Opal was annoyed that Tennant could make nothing of it. Then came the thought: _What cover must your body have not to be conspicuous?_ Tennant wondered, cynically, what would happen if he were to demand a costume of mediaeval motley, complete with Pied Piper's flute. He received quick reproof that made his head ring as from a blow. He asked Opal where and when they were going, was informed that he would soon emerge on Earth where he had left it. That told him everything but the date and season. Opal, like the rest of the captors, seemed to have no understanding of time in a human sense.