fter the revelation at the end of Season 2 that the president will not run for re-election, Season 3 begins with Selina, eyeing a promotion, courting Iowa Caucus voters at a signing of her new book. Soon, however, she learns that the Secretary of Defense, war veteran Danny Chung, is resigning - setting the stage for a possible clash with her nemesis in the presidential primaries.

Overview from themoviedb.org