Orphans of the Tide

When a mysterious boy washes in with the tide, the citizens believe he's the Enemy - the god who drowned the world - come again to cause untold chaos. Only Ellie, a fearless young inventor living in a workshop crammed with curiosities, believes he's innocent. But the Enemy can take possession of any human body and the ruthless Inquisition are determined to destroy it forever. To save the boy, Ellie must prove who he really is - even if that means revealing her own dangerous secret.... 

The seas have parted to reveal the remains of humanity's lost empire and opened a path from Shipwreck Island to the Enemy's City. Now only Ellie Lancaster and her orphan friends can prevent a terrible war. As Kate marches north at the head of her army, panic infests the City as the Enemy's strength grows. For the parting of the seas has also uncovered the Eternity Engine, a dreadful machine from before the Drowning, with the power to remake the world - or destroy it forever....