The world has fallen into smoke and smog. Below the city in the sky is the slums, a place where criminals and the less well-off reside. Life on the ground is short ans sickly. Meanwhile, above the poisonous clouds is where the rich and the healthy live in supreme delight. There is no sickness, and no crime. It is a utopia that all citizens below strive to obtain. Very few can obtain passage to Vostok, and those who do are never seen again.