In a classic "Twilight Zone" episode from 1960, an American on a walking trip through central Europe gets caught in a raging storm. Staggering through the blinding rain, he chances upon an imposing medieval castle. It is a hermitage for a brotherhood of monks. The reclusive monks reluctantly take him in.

Later that night, the American discovers a cell with a man locked inside. An ancient wooden staff bolts the door. The prisoner claims he's being held captive by the "insane" head monk, Brother Jerome. He pleads for the American to release him.

The prisoner's kindly face and gentle voice win him over. The American confronts Brother Jerome, who declares that the prisoner is actually none other than Satan, "the father of lies," held captive by the Staff of Truth, the one barrier he cannot pass.

This incredible claim convinces the American that Jerome is indeed mad. As soon as he gets the chance, he releases the prisoner—who immediately transforms into a hideous, horned demon and vanishes in a puff of smoke!

The stunned American is horrified at the realization of what he has done. Jerome responds sympathetically. "I'm sorry for you, my son. All your life you will remember this night and whom you have turned loose upon the world."

"I didn't believe you," the American replies. "I saw him and didn't recognize him"—to which Jerome solemnly observes, "That is man's weakness …and Satan's strength."