Angelo Tetrochini escapes from a family of powerful father to write. Ten years later in Buenos Aires, he meets the young and naive brother, Benny. Angelo, as he wanted, became a writer, he has a nickname - Tetro and is about to publish an autobiographical play. The youngest brother finds and reads secretly the unfinished manuscript, supposing that it contains all the impartial truth about their family. After a quarrel with his brother, Benny even adds the ending of the play. When the play is staged, the finale will be quite different, because the truth is always more difficult, deeper and more frightening.