Cruise portrays this character Jack, who lives in this distortion alternative future in which the Earth has been abandoned as it became a near impossible environment to live at.
This happened due to the destruction of the Moon by some mystery aliens, by the entire plot gets a completely unexpected twist, when he finds out that aliens he was chasing wit deadly drones, are in fact the humans just like him.
He finds about the truth and it is not nice.
I will not tell you the whole thing, because I believe you should enjoy in this one.