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

Celaena Sardothien, feared assassin, has come for retribution. Celaena Sardothien has been sent by the Assassin’s Guild to a remote island in a tropical sea in order to collect on a debt owed by the Lord of the Pirates. But when Celaena learns that the agreed payment is not in money, but in slaves, her mission suddenly changes-and she will risk everything to right the wrong she’s been sent to bring about.