Rick Riordan 
Staff of Serapis [EPUB ebook] 

The Staff of Serapis is a high-octane new story from Rick Riordan, set in the thrilling and dangerous world of Percy Jackson. Annabeth Chase is about to encounter more than she expects in the New York subway: a vicious two-headed monster and a young, blonde girl with mysterious powers — Sadie Kane! Together, magician and demigod must face Serapis, a terrifying god who draws his power from both Greek and Egyptian mythology and is bent on global conquest…Includes an exclusive sneak peek at the first chapter of The Blood of Olympus — the final book in the Heroes of Olympus series!