The Throne of Fire (The Kane Chronicles Book 2)

Ever since the gods of Ancient Egypt were unleashed in the modern world, Carter Kane and his sister Sadie have been in trouble. As descendants of the magical House of Life, they command certain powers. But now a terrifying enemy - Apophis, the giant snakes of chaos - is rising. If Carter and Sadie don't destroy him, the world will end in five days' time. And in order to battle the forces of chaos, they must revive the sun god Ra - a feat no magician gas ever achieved. First they must search the world for three sections of the Book of Ra, and then they have to learn how to chant its spells...