Four Calling Birds

First Sergeant Mack McClanahan always wanted a big family. When his wife couldn't give him one, she left him, so he'd have a chance to fulfill the dream with someone else. He couldn't convince her that the only thing he really wanted was her… that she was all the family he needed.
Now he's retired, alone, living like a hermit trying to forget what he lost.
Then he gets a call from an Army buddy, now spy, asking him to hide an agent after their cover was burned. To his utter shock, his ex wife shows up with a knife wound in her stomach, needing his protection.
Before he gets his old team together, he asks her, "Who did this to you?"
Four Calling Birds is the first in the Mourningkill series. All of the books can can be read as a standalone. No other books must be read before this.