Living isn't easy in the lower levels of the Ring System, a floating civilization constructed when Earth was abandoned as a nature preserve. Sixteen-year-old Mitsu got a job washing windows for the wealthy residents of the upper levels after his father, also a window washer, fell from his tether. Now Mitsu's been asked to man an illegal craft that's descending to the surface of the earth. But it seems everyone in this divided society has a secret agenda. Mitsu alone must decide if he's ready to take the journey of a lifetime...