First off, this volume is strictly filler and is not related to the current 4th Ninja War arc.
This volume is centered on Kakashi and follows his adventures fdom the moment he killed Rin to when he passed Naruto, Sasuke, and Sakura onto Team 7. I love this volume because it takes you into the mind Kakashi and really showcases the character development. If you've seen the Kakashi Gaiden episodes, then you know how much of a jerk he used to be. Here we see an almost broken Kakashi, one who harbors a darkness and an almost pessimistic view of life. You see how the third and fourth Hokage helped Kakashi become the ninja you've known since the original Naruto began.
Plus you get to see the back stories of Yamato's and Itachi's time in the Anbu serving with Kakashi.