The planet had been colonized for two centuries now, and produced organic compounds of great value from indigenous plants, most of which were used in textile manufacture. There were no local endemic infections to which men were susceptible. A number of human-use crops were grown. Cereals, grasses and grains, however, could not be grown because of the native ground-cover motile-stem plants. All wheat and cereal food had to be imported, which fact severely limited Maya's population. There were about two million people on the planet, settled on a peninsula in the Yucatan Sea and a small area of mainland. Public-health surveys had shown a great many things about a great many subjects ... but there was no mention of anything to account for the failure of the spaceport to respond to arrival calls from space. Naturally! The Med Ship drove on down, and the planet revolved beneath it. As Maya's sunlit hemisphere enlarged, Calhoun kept the telescope's field wide. He saw cities, and vast areas of cleared land where native plants were grown as raw materials for the organics' manufacturies. He saw very little true chlorophyll green, though. Mayan foliage tended to a dark olive color. * * * * * At fifty miles he was sure that the city streets were empty even of ground-car traffic. There was no spaceship aground in the landing-grid. There were no ground-cars in motion on the splendid, multiple-lane highways. At thirty miles altitude there were still no signals in the atmosphere, though when he tried amplitude-modulation reception he picked up static. But there was no normally modulated signal on the air at any frequency. At twenty miles--no. At fifteen miles, broadcast power was available, which proved that the landing-grid was working as usual, tapping the upper atmosphere for electric charges to furnish power for all the planet's needs. From ten miles down to ground-touch, Calhoun was busy. It is not too difficult to land a ship on rockets, with reasonably level ground to land on. But landing at a specific spot is something else. Calhoun juggled the ship to descend inside the grid itself. His rockets burned out pencil-thin holes through the clay and stone beneath the tarmac. He cut them off. Silence. Stillness. The Med Ship's outside microphones picked up small noises of wind blowing over the city. There was no other sound at all. --No. There was a singularly deliberate clicking sound, not loud and not fast. Perhaps a click--a double click--every two seconds. That was all.