Oh, John Green, I do love you, even when you say you're writing something terrible. Because this, while certainly lacking the polish of Paper Towns, actually has some great discussion fodder in it. 
 Mia is the last member of her family standing. Her parents and sister have all been Z'd up, infected with the virus spread by, of all things, corn. It's not quite right to call them zombies; they're not undead, exactly, but rather slaves to the corn, planting and tending the corn plants to the exclusion of anything else. Nobody's lurching around threatening to eat Mia's brain, but if the Z'd up catch her, they're likely to force-feed her that same corn and spread the virus that way. Mia's not totally alone in the world--she finds Caroline hiding out in a library vault, and while they have certain ideological differences on the infected, they develop the kind of friendship you can only establish when you're the last two people left on earth (or at least in Chicago). 
 Besides the obvious theme of End Times (I think zombies have become their own subset of apocalyptic and post-apocalyptic literature, along with Environmental Damage and Nuclear War), there's good discussion fodder here of sustainable food and healthy eating, and specifically the idea that corn is in everything we eat, and how does that impact our health? (For this alone, this is an interesting read coming off a cursory skimming of Michal Pollan's book.) 
 This is John Green without editing: the hyper-kinetic voice of the Vlog Brothers shines through in a likable, though damaged, teen doing the best she can in circumstances she never could have anticipated.