Henry Burton, a young and passionate political idealist, is drawn into the campaign of Jack Stanton, a charismatic Southern governor aiming for the Democratic Party's presidential nomination. As the grandson of a civil rights leader, Henry finds himself inspired by Jack's genuine warmth and empathy.
Joining the governor's close-knit team of advisors, Henry collaborates with Jack's strong-willed wife, Susan Stanton, the unconventional strategist Richard Jemmons, and the clever spokeswoman Daisy Green. They embark on a crucial journey to New Hampshire, the first primary state, where Jack hopes to make an impact.
Following a remarkable debate performance, the campaign faces a challenge when Henry's ex-girlfriend questions Jack about his controversial past, particularly an arrest during the anti-war protests at the 1968 Democratic Convention. It is revealed that Jack had to call a U.S. senator for assistance in getting released and had his police record expunged, leading to concern among the team about how this information could be weaponized against him by opponents and the media.
To further investigate potential scandals, they hire an old acquaintance, the tough yet unstable Libby Holden. In her quest to uncover the truth—especially about Jack's reputation for womanizing—Libby encounters Cashmere McLeod, Susan's hairdresser, who presents taped conversations that suggest an affair with the governor. However, Henry uncovers that these tapes have been manipulated. Libby is determined to find the source of the deceit and confronts the man behind the tapes, forcing him at gunpoint to confess his wrongdoing in a public letter.
As the campaign evolves, a new crisis emerges when "Fat Willie" McCollister informs Henry that his daughter Loretta, a former babysitter for the Stantons, is pregnant and that Jack is the father. Henry and Howard Ferguson persuade Willie to keep silent while they arrange for a paternity test. The scandal weighs heavily on Henry, igniting a mix of concern and revulsion.
With Jack trailing in the polls, the campaign shifts to an offensive strategy, targeting his closest rival, Senator Harris, over his anti-Israel votes and proposed cuts to Social Security. In a heated confrontation during a radio talk show, Harris suffers two heart attacks, leading to his withdrawal from the race and the rise of Fred Picker, a straight-talking former Florida governor who poses a significant challenge.
Jack and Susan send Henry and Libby to delve into Picker’s past, revealing his former cocaine addiction and tumultuous marriage. However, the team's decision to leak this information to the press causes tension, especially when Libby threatens to expose Jack’s tampering with the paternity test. Tragically, Libby takes her own life, struck by the disillusionment of realizing that the politicians she revered are deeply flawed.
Haunted by Libby's death, both Jack and Henry feel compelled to confront Picker and apologize for their past actions. Picker, showing integrity, admits his faults and chooses to withdraw from the race in support of Jack. Despite his discontent with the political world, Henry is urged by Jack to stay, as they still have a chance to make history.
In the months that follow, President Jack Stanton and Susan share a dance at the inaugural ball. As they celebrate this momentous occasion, Henry, reflecting on his journey, shakes the hands of the campaign staff, the last of whom is himself—a bittersweet reminder of his path through politics.
