My Mexican Bretzel opens with black-and-white clips of pilots during World War II in Switzerland, subtitled with excerpts from – so we are told – the diary of Vivian Barrett. She talks about herself and her husband Léon, who partly lost his hearing in an accident with his plane and could no longer fly. The couple's glamourous life then unfolds in diary excerpts and footage shot by Léon, about whom we also learn that he developed a successful anti-depressant, and had an obsession with many different forms of transportation.