It followed that alienness meant just that. A man who wasn’t Man--homo sapiens--could never have children with a human wife. Marie Di Costa was human, and had a real tear-soaked human daughter to prove it. Arthur Di Costa had no children. Brent pressed the window release and it sank into the casement with a soft sigh. The city noises washed in along with the fresh smell of growing things. The light breeze carried the fragrance in from the Jersey woodlands. It seemed a little out of place here above the gleaming city. Leaning out slightly, he could see the moon riding through the thin clouds and the morning star, Venus, just clearing the eastern horizon. He had been there on the moon. He had watched them assembling the first Venus rocket. Man, the erect biped, was the only sentient life form he had ever seen. If there were others, they were still out there among the stars. All, that is, except one ... or could there possibly be others here on Earth? This was useless thinking though. Don’t invent more monsters until you’ve caught your first. A night’s sleep first. After that, he could start setting his traps out tomorrow. * * * * * For the tenth time, Brent threw a half-eaten candy bar into the receptacle and started down the street. Being a private eye was so easy in the teleshows--but how different the reality was! He had been shadowing Arthur Di Costa for three days now, and it was ruining his digestion. Whenever his quarry stopped, he stopped--often on the crowded city streets. Loitering was too obvious, so he found himself constantly involved with the vending machines that lined the streets. The news sheets were easily thrown away, but he felt obliged at least to sample the candy bars. Di Costa was just stepping onto the Fifth Avenue walkway. Brent got on a few hundred feet behind him. They rolled slowly uptown at the standard fifteen miles per hour. As the walkway crossed Fifty-Seventh Street, a small man in a black and gold business suit stepped briskly onto it. Brent noticed him only when he stopped next to Di Costa and tapped him on the shoulder. Di Costa turned with a smile--which changed slowly into a puzzled expression. The little man handed what appeared to be a folded piece of paper to the surprised painter. Before Di Costa could say anything, the man stepped off the walkway onto a safety platform. With a quick movement, surprising in a man of his chunky build, he vaulted the guard barrier and stepped onto the downtown walkway. Brent could only stare open-mouthed as the black figure swept by him and was lost in the crowds. Surprised by the entire action, he turned back to find Di Costa staring directly into his eyes! Whatever course of action he might have considered was lost. Di Costa took the initiative. He smiled and waved. Brent could hear his voice faintly through the street noises. “Mr. Dalgreen, over here!”