In the year 2218, Earth has flooded. With no choice but to adapt, humans now receive injections at the age of 16 which allow them to grow gills and a tail. Children are forced to stay in airtight buildings, known as Walker's Wings, until they are old enough to handle the injections and the change they provide. However, when Earth's water begins to disappear, the children of Walker's Wing 17 may be the only ones who can stop it.