There is an episode of The Twilight Zone in which a normal American neighborhood is thrown into violent chaos by the appearance of a strange object in the sky. The fear that alien invaders might be masquerading as a human family causes neighbors to turn with suspicion on those they’ve known all their lives.
Like so many Twilight Zone episodes, the true monster here is Man. The lesson is that the enemy’s best weapon is the seed of paranoid doubt we harbor against those closest to us. It is a not-so-subtle commentary on McCarthyism’s hysterical campaign to root out the communist threat by encouraging citizens to denounce their friends and allies.
The communist, like the aliens in The Twilight Zone, is so dangerous precisely because its otherness cannot be easily recognized. Soviet sympathizers can look exactly like everybody else, and the possibility of their presence among us is so terrifying because it challenges our confidence in our own capacity for self-recognition. The identity of friends, spouses, teachers, and politicians cannot be trusted precisely because they look just like us. Familiarity itself becomes suspect as the mask of a dangerous otherness.