Mitch is not young anymore. He used his youth to gain lot of experience in dealing with really horrible persons. It is scary to know that he would not hesitate to kill if he thought that person would do harm to innocent people.
So when he was hunting down a terrorist head, he go at it with all he got. And he almost got it.
Now it is the turn of the terrorist to hunt him back.
He got more than one side of of enemy that he has to deal with. An crazy politician is running for president and is likely to get in position. This is a mean bitch who is pretty selfish and would do anything, including harming innocent people if she could gain more vote and more power.
The rest is just a bit of nicely laid out plan that could work if there is no one to stop the bad guys.
The use of deadly virus in the plot is very timely and scary as well.