The silent invaders

by Robert Silverberg

"The Silent Invaders" by Robert Silverberg is a science fiction novel published in 1963. Earth becomes a prize in an ancient galactic conflict between two alien species who dispatch surgically altered agents to infiltrate human society. Major Abner Harris, a Darruu operative, discovers his Medlin enemy has been subverted by telepathic human mutants evolving toward transcendence. He must choose between his hostile alien superiors and joining a conspiracy that demands he betray everything he knows.