I actually read Z for Zachariah in middle school, and it's a really good book. o: It's about this girl, Ann Burden, who is (she assumes) the last person alive after some sort of nuclear apocalypse -- when she meets and nurses a wounded man called John Loomis, and the two end up in a life-or-death conflict. I have no idea what part Chris has, since IMDB says that Chiwetel Ejiofor was cast as Loomis. He and Ann are literally the only two characters in the book.
i guess chris pine was typecast to play the part of the apocalypse