 Why had Roger been trained by Opal?
If it only had a lease that could be broken— Roger Tennant, crossing the lawn, could see two of the three wings of the house, which radiated spoke-like from its heptagonal central portion. Dana was lying under a tree near the door, stretched out on a sort of deck chair with her eyes closed. Above it her comely face was sullen beneath its sleek cocoon of auburn hair. He had thought them up in a moment of utter boredom and they were extremely comfortable. However, the near-Buchanan tartan did not crease or even wrinkle when he moved. Their captors had no idea of how a woven design should behave. He could sense the restless stirring of the woman within Dana, just as he could feel the stirring toward her within himself—desire that both of them loathed because it was implanted within them by their captors. Within the dome of the barrier, it looked more like a well-kept if bizarre little country estate. The brook was practically water, but the small stones over which it flowed were of no earthly mineral. They entered the house, which had no roof, continued to move beneath a sky that glowed with light which did not come from a sun or moon. Eudalia, who had borne twin girls recently, was lying back, newly thin and dark of skin and hair, smoking a scentless cigarette. A tall woman, thirtyish, she wore a sort of shimmering green strapless evening gown. Tennant wondered how she maintained it in place, for despite her recent double motherhood, she was almost flat of bosom. Eudalia had been a female foreman in a garment-cutting shop before being captured and brought through. He turned to Olga, broad, blonde and curiously vital, who sat perfectly still, regarding him over the pregnant swell of her dirndl-clad waist. Olga had been a waitress in a mining town hash-house near Scranton. Tennant wanted to put an encouraging hand on her shoulder, to say something that might cheer her up, for she was by far the youngest of the three female captives, barely nineteen. "But he doesn't have to—have them," objected Olga. In fact, Tennant thought, only her laughter was unpleasant, a shrill, uncontrolled burst of staccato sound that jarred him to his heels. It arrived before the meal, materializing against one of the seven walls of the roofless chamber. Tennant watched the girls as a sweet-voiced crooner began to ply an unfamiliar love lyric to a melody whose similarity to a thousand predecessors doomed it to instant success.
 because Opal was unable to bring other men back
 because Opal wanted to further his experiment  because Opal needed help building a new gateway  because Opal was looking for someone to take his place  because Opal was unable to bring other men back