Imagine a planet entirely covered in clouds. . . .
Imagine peaks rising out of the cloudscape. . . .
Imagine a citadel standing on each peak. . . .
Heliopolis. A citadel divided into five layers, every citizen sure of their place and purpose. But there is one uncertainty that haunts all Heliopolitans. What lies beneath the thick ocean of cloud? A vast abyss? The fiery realm of the gods?
Fourteen-year-old Marcus is about to find out.
When his father fails to return from a diplomatic mission, Marcus joins an expedition across the cloudscape in search of him. But he discovers too late that danger lies closer to home—somebody wants him dead. And when his airship is attacked, Marcus is plunged into a terrifying new world beneath the clouds. . . .