After the Watergate scandal of 1972 and his subsequent resignation in 1974, 400 million people worldwide watched Nixon leave the White House. Among them is British journalist David Frost, currently recording a talk show in Australia, who decides to interview Nixon.

Nixon’s literary agent, Irving Lazar, believes the interview would be an opportunity for Nixon to salvage his reputation, and to make some money. Lazar demands $500,000, and ultimately gets $600,000 and Frost accepts.

After persuading his friend and producer John Birt that the interviews would be a success, Frost travels with Birt to California to meet with Nixon. On the plane to California, Frost flirts with a young woman called Caroline Cushing, and they begin a relationship.

Frost struggles to sell the interviews to American networks, and decides to finance the project with private money and syndicate the broadcast of the interviews. He hires two investigators — Bob Zelnick and James Reston Jr. — to help him prepare, along with Birt. Frost is not clear on what he wants from the interview, and Reston encourages him to aim for a confession from Nixon.

Under scrutiny by Nixon’s post-presidential chief of staff, Jack Brennan, Frost and Nixon embark on the first three recording sessions. Frost is restricted by an agreed-upon timeframe and, under pressure from his own team, attempts to ask tough questions, but Nixon dominates the sessions regarding the Vietnam War and his achievements in foreign policy. Behind the scenes, Frost’s editorial team is nervous about the interviewer’s technique and angry that Nixon appears to be exonerating himself.

Four days before the final interview, which will focus on Watergate, Frost receives a phonecall from an inebriated Nixon. In a drunken rant, Nixon declares that they both know the final interview will make or break their careers, and compares himself to Frost, insisting that they both came from humble backgrounds and had to struggle to make it to the top of their fields, only to be knocked back down again. Frost gains new insight into his subject, while Nixon assures Frost that he will do everything in his power to emerge the victor from the final interview.

The conversation spurs Frost into action. He works relentlessly for three days to prepare, while Reston pursues a lead at the Federal Courthouse in Washington.

As the final interview begins, Frost ambushes Nixon with damning transcripts of a conversation between Nixon and Charles Colson that Reston dug up in Washington. As his own team watches in horror from an adjoining room, Nixon admits that he did unethical things, adding, “When the President does it, that means it’s not illegal.” A stunned Frost is on the verge of inducing a confession when Brennan bursts in and stops the recording. After Nixon and Brennan confer, the interview resumes, Frost aggressively pursues his original line of questioning, and Nixon admits that he participated in a cover-up and that he “let the American people down.”

After the interview, Frost and Caroline pay a farewell visit to Nixon at his villa. Frost thanks Nixon for the interviews and Nixon, graciously admitting defeat, thanks Frost in return and wishes him well, privately adding that he has no recollection of calling Frost while drunk. He also for the first time addresses Frost by his first name. Nixon watches Frost and Caroline Cushing leave and then leans over a railing of his villa, looking out at the sunset.

An epilogue states that the interviews were wildly successful and that Nixon never escaped controversy until his death in 1994.