Alan voiced my realization. "Why, that's this dawn we've been seeing! That tower--in the park behind us--that policeman is out there now--he saw it! That's today! That just happened--now!" CHAPTER II THRESHOLD OF A MYSTERY It was clear to us, or at least in part, what had occurred. The little fragment of Space occupied by Central Park, was throughout both the visions, what we had been seeing. The tower was there; the tower had not moved--in Space. We had first seen it in some far-distant realm--of Time. And it had moved, not in Space, but in Time. We had glimpsed the tower almost stopping, frightening those savages who, in what we call the Past, were roaming this little island of Manhattan. The same Space. The same inclosing rivers. But no city back then. Or perhaps, near the southern end, where the converging rivers merged in broader water, there might just then have been a group of struggling settlers. Cabins of hewn, notched logs, stockaded against the marauding redskins of the adjacent forest. A dense forest then, was north of the trail called "Maiden Lane." Far up there was this Space which now we call Central Park, with the great New York now around it, grown in three short centuries from the infant New Amsterdam. And the tower, immovable in Space, had come in Time to 1945. Had paused. Now. This very morning. Had stopped; and frightened a policeman of 1945, in Central Park. And then had become again a phantom, and in another instant, wholly invisible. I recall my surprise at Alan's apparent understanding of this incredible thing which had come, all unheralded, upon us. I found suddenly that there were things in the life of Alan which I did not know. Things he shared with Nanette; but not with me. An eagerness was in his manner as we discussed this thing. His dark cheeks were flushed with emotion; his dark eyes had a queer glow of excitement. "I think, Ed, that I can understand a good many things of this. Things father knew, in theory--things he told me--" He checked himself. And when I questioned, he stopped me. "Wait, Ed. It's confusing. It seems--tremendous." He stumbled over the word, but repeated it. "Tremendous." And then he added: "And perhaps--dastardly." What could he mean by that? Nanette said: "But, Alan--that girl--there was a girl, came here to New York this morning--" The girl! The shadow girl, from out of the shadows! She, at least, was something tangible now. We had seen her in Central Park this morning. The television screen now was vacant. It was destined never again to show us anything, but that we did not know. We had seen a girl arriving? Then, if so, she must be here--in Central Park, now.