After one of Twilight's spells goes horribly wrong, the six mares are thrusted into a cross-dimensional portal into a whole new world called Earth. There they discover many things in this new world, one thing being that it's an exact copy of Equestria; just named something else. The trees, similar organisms, and similar plants; but one thing the girls discover is religion; but after bringing all these ideas back to Equestria with them is when the real trouble started.
'A Seemingly Normal Day' is an alternate version of chapter 1 written in second person; it is optional, you don't have to read it, it just gives a bit of backstory to the character that first meets the girls on Earth