The Mightiest Man

A man abducted and interrogated by extraterrestrials trades human knowledge for promised rewards and is granted apparent immortality plus remote power to kill or immobilize others. When his betrayal becomes known he is lynched by enraged crowds, later put on trial, and causes panic by demonstrating his powers; yet he cannot be executed. The invaders are ultimately defeated by pervasive fungoid organisms that infest and incapacitate their brains, forcing them to depart, but the man remains alive and dangerous because his abilities depend on his intact mind, leaving authorities contemplating whether his consciousness could be covertly removed to neutralize him.