Patricia A. McKillip 
Alphabet of Thorn [EPUB ebook] 

Deep inside a palace on the edge of the world, the orphan Nepenthe pores over books in the royal library, translating their languages and learning their secrets. At sixteen, she knows little of the outside world. But when a young mage gives Nepenthe a book that has defied translation – a book written in a language of thorns – it speaks to Nepenthe’s soul, and becomes her secret obsession. As the words escape the brambles they reveal themselves – and begin to reveal Nepenthe’s destiny …