The Brain Sinner

An invisible network of human minds lay across the country, delicately tuned, waiting breathlessly for the first spark of contact from the unknown ... from the unpredictable telepathic Alien.
The ship skimmed down like a shadow from the outer atmosphere and settled gently and silently in the tangled underbrush of the hill that overlooked the bend in the broad river. There was a hiss of scorched leaves, and the piping of a small, trapped animal. Then there was silence.
Higher up, the sunlight was bright over the horizon; here the shadows had lengthened and it was quite dark. Far across the hills a dog howled mournfully; night birds made small rustling sounds through the scrub and underbrush. The alien waited, tensely, listening, waiting with his mind open for any flicker of surprise or wonder, waiting for a whisper of fear or recognition to slip into his mind from the dark hills around the ship. He waited and waited.
Then he gave a satisfied grunt. Foolish of him to worry. All possible care had been taken to avoid any kind of alarm. He had landed unseen from Io.
The alien stretched back against the couch, allowing his long, tight muscles to relax, as he sent inquiring feelers of thought out from the ship, probing gently and tentatively, for signs of the psi-presence. The landing, after all, had been assumed. Already the natives had convinced themselves that ships such as his were a delusion. Such simple creatures, to disregard the evidence of their own senses! There should be no problem here when the invasion began, with the preliminary studies already completed, the disguising techniques almost perfected. A primitive world, indeed, but a world with psi-presence already developing—a possible flaw in the forthcoming silent conquest.
For psi-presence could detect other psi-presence, always, anywhere, despite any disguise. The alien knew that. It was the one universal denominator in all the centuries of conquest and enslavement in his people's history. Before they could come, they must know the strength of the psi-presence on this world.