"A Long Journey" tells the story of three siblings who reach adolescence in the late 1960's. The documentary's storyline follows the youngest brother's travels around the world. Worried that he would enter the struggle for freedom against the Brazilian dictatorship, his family sent Heitor to London. There however, he dives head on into the "Swinging London" and, just like the European and American youth of the time period, he experiments with drugs and the mystic allure of India. In the nine years he has traveled around the world, from 1969 to 1978, he has regularly written to his family. The documentary features interviews with Heitor today, his letters and off-screen comments of Heitor's sister, Lúcia Murat, the director of the movie.

Em 1969, durante a ditadura no Brasil, uma família envia o caçula para fora do país a fim de evitar seu engajamento na luta armada, como fez a irmã. Heitor viaja pelo mundo ao longo de nove anos e, durante esse tempo, envia cartas aos parentes.