In the giant steam city "Cogswell", class is as cold as steel. Karen, a genius mechanic, lives at the bottom of Gear City. His only belief is to protect his sister. However, when a strange disease called "Ethel Decay Disease" takes away his sister's vitality, he is forced to embark on a bloody trial leading to the "Tower Zone" in the clouds.
What he hides is the forbidden talent - "Whisper" - that resonates with the mechanical and mysterious energy "Etel". This power is both his hope and what makes him a heretic in the eyes of the city's iron-fisted rulers.
From saving one person to rebelling against the world, when he discovers that his sister's illness is just a huge conspiracy to cleanse "others", Karen must make a choice: continue to hide, or embrace this cursed power and send the most decisive whisper to this rusty world?
