The City was built on a sharp mountain that jutted improbably from the sea, and the sea kept trying to claim it back. That grey morning, once the tide had retreated, a whale was found on a rooftop. 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.