What makes a woman cover her hair, or go further and cover her body and her face?
This question had preoccupied the Brazilian filmmaker Betty Martins for a long time as she walked around London, where she has lived for eight years, noticing more and more visibly Muslim women on the streets.
"Everything I knew about Muslim women was through the media, and the discourse was always negative, about oppression and backwardness. People would generally see a woman wearing a hijab and feel sorry for her, or assume she had been forced to wear it," she says. "But at the same time, the Arab Spring was happening and Muslim women were being involved and that made me think: 'Wait a second'. The more I started reading about it, the more I realised there were lots of very strong Muslim women. I wanted to explore that."