In March 1936, White House staffer Paul Duroc dies of cyanide poisoning while having drinks with purchasing agent Therese Rolland, and she is charged with the murder. Believing in the young woman's innocence, the First Lady decides to assist the investigation of Secret Service agent Stan Szezygiel and Washington, D.C., Det. Lt. Edward Kennelly. Meanwhile, FDR is marshaling support for his 1936 reelection, a job made easier since the assassination six months earlier of Louisiana candidate Huey Long. Backroom information and campaign machinations tie Duroc to the Long machine, leading the First Lady, Szezygiel and Kennelly deep into Louisiana power circles to find the killer.