From the beginning to the end Carter is on a killing spree in order to ensure an impossible cure for a virus, which at first hit North Korea. The cure is impossible because you can't develop a vaccine from the blood of one survivor (it only works in Hollywood), and the virus makes no sense either in terms of contamination, incubation, symptoms, recovery, etc.
The pseudo-plot relies on murdering 300-400 people (I lost count) along the way, and in the end turns out that everything was done for naught. Yet, digging a little (femtometers will suffice) under the surface of the movie, the whole thing could have ended at the beginning or at any point in the movie: the threesome Carter, a "scientist" (the actor who was great in "The plan man", and should have avoided being associated with this trash), and the latter's daughter, was needed for the killing to go on.
Pure nonsense, just like the US president with the same name.