Fallout is the fourth in the Vampire War series. A few months following the conclusion of the previous installment, Dark Nation, the DSA task force has reclaimed the White House and a portion of Washington, D.C. Meanwhile, the new Vampire Master has taken over the city of New Orleans and its outlying areas. They've set up operations in an old school with a plan to destroy Washington and the surviving members of the task force with a nuclear weapon. With more research, the tsak force discovers a possible method for finally ending the war and eliminating the vampire threat forever.