At a time when France is facing street protests about social injustice, a comedy about homeless women in the north is being tipped as one of the funniest and most moving films of the year.

Les Invisibles, which opened in French cinemas on Wednesday, tells the story of women sleeping rough in northern France as a social work centre is threatened with closure.

Facebook Twitter Pinterest A trailer for Les Invisibles

Many the main characters are played by former homeless women who are not professional actors. Adolpha van Meerhaeghe, 70, who plays one of the homeless characters, used to sleep rough outside Lille station and served time in prison for the manslaughter of her violent husband before writing a book about her story.

She said her “big mouth” served her well on the streets and helped with her acting. “It’s hard to sleep outside and keep your personality. Humour kept me alive.”

The film – in which the homeless women adopt pseudonyms like “Lady Di” and “Brigitte Macron” (the French president’s wife) – was feted at the Angoulême film festival last year as an ode to “the modern women of the resistance” – those on the streets and the female social workers helping them. Several other French festivals have given the film awards.

The director, Louis-Julien Petit, known for his earlier film Discount, about supermarket workers in the former Nord-Pas-de-Calais, spent a year volunteering in women’s homeless shelters in Grenoble and Paris, saying he wanted to get the tone of the film right. “I had a lot of preconceived ideas but when I was in the shelters, what I found was people who were just like me,” he said.

Facebook Twitter Pinterest From left: Corinne Masiero, Louis-Julien Petit and Deborah Lukumuena at the Angoulême film festival. Photograph: Yohan Bonnet/AFP/Getty Images

Corinne Masiero, a French actor who plays a social worker, said the film worked because of its “mix of humour and seriousness”, which meant the audience did not look down on the women but saw them as equals. “The viewer realises anyone could end up in that situation themselves,” she said. She revealed that in her teens and early 20s she had also slept rough as she struggled with addictions.

Masiero, who once ran for municipal elections for the leftwing party La France Insoumise (France Unbowed), told Le Parisien she was a supporter of the ongoing gilets jaunes anti-government protest movement and had demonstrated several times. “How can you respect a system that hands privileges to people who are already ultra-privileged?” she said.

Audrey Lamy, another actor, said the film “brings women who are in the shadows into the light without judging them. The laughter makes you think.”