The story of Moments of Paranoia is as follows: there has been an accident in a laboratory where they were studying some kind of shape-shifting mutant (similar to The Thing). After it kills many laboratory workers, only three people are still alive. One of them is the creature, which has taken human form.
Now, you (the only one of the three survivors with a gun) must try to figure out which of the other two is the creature by asking them different questions. In addition, you have to do so quickly, as the room will fill with gas in less than five minutes and all of you will die.
Moments of Paranoia is a short adventure game in which you will have to make a very important decision. You can shoot either of the other two at any time, but you will never know for sure if you made the right decision... if there is such a thing.