The last man on earth sat alone in a room. There was a knock on the door.” - Frederic Brown
The two sentences are in conflict. The author knows this but presents them to you with no explanation, leaving you, the viewer to reconcile them. You can believe or disbelieve the first sentence, the second, or both. Through your shared curiosity, the man in the room becomes instantly relatable, and the person on the other side of the door is instantly fascinating. Even though you know nothing about them.