They are from the future on a mission to save the mankind from the imminent danger. They have to travel between future and now everyday, and they have a 12 hour window to do so. If they fail to travel back they will be left here for ever or even worse they will evoparate into thin air.
Now, by asking questions (millions in number) they analize the mindset of current day people and identify the root cause of the end of the world. In fact, the cause is not one it was the crazy and inevitable combination of set of causes. Einstein Pain Waves (EPW) was one of them. The mission is to create an artificial paradigm shift in the mindset of the people towards everything that can be potential cause for the end of the world.
More difficult, the alien race from a distant planet PRAVOK is curiously waiting for the lifeless earth to extend Thier existence. They do not want to waste the energy or effort to end life on earth as they know earth is destined to perish soon. But, the aliens have traced that the people from future are on the mission to save the earth against their wish.
How the people from now got to know about the people from the future and how collaboratively won overover the alein race to protect earth is the plot.