I'm reading Wool - by Hugh Howey
Amazing series of books. It's set in a silo built underground in a post apocalyptic earth. One of the best books I've read in a LONG time.
Basically there are loads of levels of the silo. The only way to get to them is stairs. Each level does different things like there is a farming level, IT level, mechanics level. The more important people live nearer the top. ALSO there are screens on the top level that show the outside world which is all barren and horrible. Every so often they send a person out in what's called 'The Cleaning' and the person has to go out and clean the sensors that project the pictures onto the screens. They always die in the process as earth is full of toxins etc now. One of the biggest mysteries is WHY do they clean these sensors when they have been sent out to die?
This isn't even giving ANYTHING away at all. There are 8 books in the main Wool series then 3 more prequel books in the 'Shift' 'Wool' series.