Y The Last Man: Unmanned, by Brian K. Vaughan et al

I read Volume One of Y: The Last Man: Unmanned, and I have also read Volume 2: Cycles and Volume 3: One Small Step. So far, so good! The first book pretty much sets up the story and introduces us to some very important characters. I don't want to go into it too much for those who haven't read it: I myself did not really know what to expect. All I heard was that the series was and is good. Sometimes, I prefer to let the story unfold as I read.  This is definitely a series for mature readers.