Following his successful attempt to petition the governor for a pardon for a boy wrongly convicted of murder, attorney Jefferson Keane (Lionel Barrymore) is welcomed home as a hero. Though Jeff doesn't care much for politics, he accepts the invitation of fellow Bar Association members to run for the United States Senate against the bombastic incumbent, Senator Bitler (Berton Churchill). Jeff wins the election, incurring the ire of Bitler and his cohorts, and becomes the butt of Washington newspapers' jokes about "the new Lincoln." The jokes soon subside when Jeff makes an impassioned speech before a special session of Congress against the control by big business of the nation's resources. Though opponents call his speech "Communistic," visitors in the gallery cheer him, and the press compliments his "plain words by a plain man." Now a celebrity, Jeff is invited to the White House, where he is approached by Consuela Fairbanks (Karen Morley), a Washington hostess who had earlier snubbed him. Lying that she heard his speech from the gallery, Consuela begins to pursue Jeff, inviting him to parties and pretending to be attracted to him. Jeff, who has been a widower for many years, admires the attentions of a beautiful young woman and dismisses his daughter Ruth's (Diane Sinclair) reservations about Consuela's motives. Soon Consuela charms and seduces Jeff into a marriage that she hopes will help her financially. Not long after their marriage, Consuela gives a dinner party which Henri Brenner (Nils Asther), her former lover, attends. She rejects Henri's advances at first, but some time later they resume their affair. Meanwhile, after confessing to Jeff that she is terribly in debt, Consuela urges him to resign from the Senate and accept a lucrative position with the law firm of Alan Hinsdale (C. Henry Gordon), a businessman whom Jeff has always mistrusted. At first Jeff wants to believe that Consuela's high opinion of Hinsdale is justified, but he gradually realizes that Hinsdale is using him to front for illegal activities. When Jeff comes home early one day and interrupts Consuela and Henri in a compromising position, he realizes that Ruth had been right all along. After Consuela leaves him, Jeff goes to Ruth, who urges him to fight a new Senate investigation of his relationship to Hinsdale and his secret partner, former Senator Bitler. At the Senate hearings, Ruth and old friends from home stand by Jeff, but the strain of testifying weakens his heart. After an impassioned plea in which a faltering Jeff says that he was guilty of bribery, but that Hinsdale has betrayed the people of the United States, Hinsdale's cause is turned over to the Attorney General for prosecution. But the strain of the speech causes Jeff's heart to give out and he collapses. After Jeff dies, his friend Stapleton (Henry Kolker) tells Ruth, "he loved his country well enough to die for it."