Percy Jackson and the Greek Heroes

The Throne of Fire: the second book in Rick Riordan's The Kane Chronicles. EVER since the gods of Ancient Egypt were unleashed on the modern world, Carter Kane and his sister, Sadie, have been in big trouble. As descendants of the magical House of Life, they command certain powers. But now a terrifying enemy - Apophis, the giant snake 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...