The Walking Dead (Volume 26) Call To Arms by Robert Kirkman.

"Rick begins training his people to act as a military to defend themselves against the Whisperers. A surprise awaits him though when Negan is let out of jail and goes to pay Alpha a visit."

4 Stars. 

Pros:  Negan has more of a character and background then one would expect. 

Cons: Sometimes the predictability of the story gets old but it's entertaining enough to keep reading. 

Full Review: 

Rick begins to train people to act as a military. Dwight takes naturally to the role as leader. Eugene, who bought a CB radio at the fair manages to get a signal and begins talking to a woman named Stephanie. They admit that they're with groups but they don't tell each other much about where they are. 

Brandon, the son of Morton, one of the men who attacked Rick, ends up getting fed up with it all and gets the keys to the jail and talks Negan into coming with him. They sneak off together when Maggie's group heads back to the Hilltop. They make it to the border that Alpha marked and after killing Brandon, Negan walks right on through. 

Rick realizes that Negan is gone and sends Michonne and Aaron after him. They're attacked by Whisperers and Aaron is stabbed. They're saved by Dwight and his crew and Michonne takes Aaron to the Hilltop for medical treatment. When asked if they're going to go after the Whisperers that attacked Michonne and Aaron, Dwight says no. That they've already passed into their territory and Alpha specifically said that would be seen as an act of war. 

Negan is picked up by the Whisperers and brought to their camp. In only a few days time, he manages to impress Alpha and she says that he is accepted into the fold. One night, Negan witnesses two men trying to rape a woman and he intervenes. Alpha explains that this is just their way and that it makes the victim either stronger by overcoming the experience or it helps cull the herd by singling out the weak. 

Negan admits that when this all started he lost someone close to him. And to deal with it, he shut down and doesn't allow himself to feel anything. Alpha admits that she tries to do the same but that she can't, that she's weak and feels emotions, especially for what she let happen to her daughter. For a moment, you think that Negan will understand and become a Whisperer, instead he cuts Alpha's throat, removing her entire head and says that Rick will love this.