Dark City Dark Night by Abe Evergreen is a fast-paced story about a man in a dystopian society trying to save a little girl from a deadly virus. Readers are only given a glimpse of his surroundings: an automated city, divided into sectors, populated by desperate and fearful people. Society has been ravaged by one virus strain after another and scientists are struggling to create new vaccines. Most people die from the various strains, but those who don't are extremely violent. Virtually nothing personal is revealed about the main character or his family. I would've like to find out why the man never wears a mask as everyone else does.
I don't mind having unanswered questions about a story or a character. There's no rule stating readers need to know everything about a backstory. I think leaving the history of a setting unexplained helps keep the focus on the characters, and giving the characters secrets keeps us hooked in hopes we will find the answers we are seeking. Through this process, we are more likely to feel we experienced a story versus being told what happened.
UPDATE: This is the first story in a mini trilogy. Read my review of the second story here.