Ender's Game, and the rest of the series.

[Zainalara]

I don't know if you're familiar with it, but I'm going to talk to you about a book that I've really loved since I discovered it - about 5 years ago now for those who are interested - and which is going to be released as a film in November.
The Ender's Game is a science fiction series written by Orson Scott Card. It's somewhat unique in its genre, as the first book, "Ender's Game," is described by the author himself as "orphaned": in other words, it stands alone.

The other books in the series continue the story, but reading them isn't necessary to appreciate the plot of the first book (I don't know if that's very clear).

Orson Scott Card has also written two other series in the same time and place as the Ender's Game: the Shadow Saga and the First Formic War, both of which are still being written.