After background about the childhood and youth of John Lennon (1940-1980) and the birth of Vietnam-War protests, the film plunges into Lennon's quest for world peace: compositions such as "Give Peace a Chance", the lie-in following his marriage to Yoko Ono, appearances at concerts, "War Is Over" posters, and plans for a series of concerts in 1972 in U.S. presidential primary states reach newly-enfranchised young voters. This plan for concerts, in particular, led a prominent Senator, the FBI's J. Edgar Hoover, and Nixon's White House to initiate a concerted and illegal effort to deport Lennon. Thirty talking heads, led by Yoko, comment on Lennon and these events.

Late in 2006, President Jimmy Carter tours the U.S. promoting his provocative "Palestine: Peace Not Apartheid." Demme's camera follows Carter from city to city, home to Plains (population 635), visiting a Habitat for Humanity site in New Orleans, and talking on radio and TV with Teri Gross, Charlie Rose, Diane Rehm, Jay Leno, Larry King, Wolf Blitzer, Tavis Smiley, and Al Jazeera and Israeli pundits, discussing Palestine's plight and the policies of Israel. Critics speak as well. Between events, Carter talks about Camp David, recent travels, being married, speaking Spanish, and wisdom he learned from Rachel Clark, his nanny. A montage of speeches, awards, and travels ends the film.