Humanity's space exploration ultimately took the form of billions of identical probes, capable of building anything (including astronauts themselves) upon arrival at their destinations. One lands in Equestria. Things go downhill from there.
Four months after the end of human civilization, six ponies come together to rebuild. They learn that the apocalypse has not made friendship any easier.
Twilight’s trip to Earth and friendship with the humans brings new friends and enemies to her peaceful world. With the specter of war hanging over them, Equestria will have to form an alliance like no other to fight the menace from the void.