A strain of the deadly Ebola virus, brought into Texas by an African dog, infects escaped felons, who are sought by the team in a desperate attempt to control the contagion.

A "dirty bomb" threatens D.C. in a suspected airborne attack mounted by terrorists flying out of western Africa, where Frankie and Kilmer seek to unravel the plot with the aid of a shrewd operative who's a former Special Forces maverick.