Trouble with Doubles

“Listen to me! Please listen! If you don't, if you won't, if you fail to understand, then the same incredible terror that's menacing me WILL STRIKE AT YOU!”
-Invasion of the Body Snatchers (1956) trailer

So might one hear some paranoid derelict rant on the streets of the City--and they just might happen to be right. The creatures called "doubles" are one of the insidious tools of subversion used by the Reds in their tireless attempt to remake the world in the image of their freedomless subterranean society.

Doubles are either an artificial lifeform created by the Reds or their former (now extinct) masters or “natural” underground creatures--perhaps selectively bred over generations to optimize their utility. Whatever their origins, doubles are force grown in gestation pods then sent to surface world to steal the identity of humans and replace them. Normally, they're spindly, vaguely humanoid creatures, unsettling in their bland featurelessness, but they can perfectly assume the form of anyone they mimic. Without the use of magic or medical tests, only the unsual glow of their eyes that can be glimpsed in certain lighting conditions gives them away--a situation the doubles seek to avoid if they can help it.

The doubles must observer humans they plan to duplicate. The longer and more detailed the observation, the better the duplication in terms of appearance and behavior. This is often accomplished by the surveillance devices of the Reds. Doubles can change forms on the fly, but their mimicry won’t be as convincing.

It’s believed Reds mostly target government officials or other important figures for replacement, but given the psychological warfare they wage against humanity, they aren’t above random replacement of regular individuals simply as an act of terror.

[Doubles are, of course, doppelgangers with a new veneer for the Strange New World. This version would work just as well in a pulp, atomic age, conspiracy, or maybe even supers game, though.]