Letters to Mum chronicles the past thirty years in Brazil, told in the form of letters by cartoon artist Henfil to his mother Dona Maria. Nessas cartas, ele discute temas como saúde pública e a questão indígena. They establish a dialogue with images of Brazil today. Besides the letter being read in a voice-over by director and actor Antonio Abujamra – artists, politicians and friends (Luis Fernando Veríssimo, Angeli, Laerte, Zuenir Ventura, Lula) speak of Henfil's life from the years of the military dictatorship until his death in 1988.
