Sarah J. Maas 
Assassin and the Desert [EPUB ebook] 
A Throne of Glass Novella

The world’s most feared assassin hones her craft…and her blade. The Silent Assassins of the Red Desert aren’t much for conversation, and Celeana Sardothien wouldn’t have it any other way. She’s not there to chatter, she’s there to learn their ways. Quiet suits her just fine-until she begins to suspect there’s a traitor in the fortress, and she must determine which of the mute and mysterious assassins is her deadly adversary.