Lights on the Nile — Donna Jo Napoli

Kepi is a young girl in ancient Egypt, content to stay home with her family, helping her father, who was wounded in the construction of a pyramid for the cruel pharaoh Khufu. But that was before she and her pet baboon, Babu, were kidnapped and held captive on a boat bound for the capital city, Ineb Hedj. And when Kepi and Babu are separated, she knows she has only one choice: to make her way to the capital on her own, rescue Babu, and find a way to appeal to the pharaoh. Khufu is rich and powerful, but Kepi has her own powers, deep inside her -- ones she herself doesn't even know about yet.