A huge machinehouse has been home to many workers, cut off from the outside world since they were put in service as children. Of the world outside they know little, just having their childhood memories (and the reader knows less). A mysterious illness is reducing their numbers, until gradually just a pair are left. The story focusses on the conversations between the two, about what might be out there (if anything) or whether they have been left behind. The answer isn’t revealed!