I read "Girl on a Train" and enjoyed it. If anyone needs a recommendation on the Sci-Fi/Apocalyptic/Dystopia genre, I highly recommend "Seven Eves" by Neal Stephenson. The story spans 5,000 years beginning with the earth being bombarded with meteor showers, causing devastation and forming an atmospheric cloud that will eventually make earth inhabitable. So earth launches an "Ark" into the atmosphere to ensure the survival of the human race.
Thanks Cheri T, for introducing me to this author:)