Eighty-six years after she was silenced at the age of 18 by four bullets that her mother fired into her sleeping body, Hildegart Rodríguez – Spanish prodigy, socialist and pioneering sexual educator – has found her voice once more.

So, too, has the trailblazing writer Carmen Laforet and, more controversially, Pilar Primo de Rivera, daughter of the 1920s Spanish dictator and crusading leader of the women’s section of the Falange movement under Franco, which was led by her brother, José Antonio.

The trio are the first influential thinkers featured in a new online project that mixes film and literature to recover and preserve the ideas, words and legacies of Spanish and Latin American women whose contributions to culture and society have been overlooked, marginalised or forgotten.

Cartasvivas (Livingletters) is the brainchild of the writer and Exeter University academic Nuria Capdevila-Argüelles and the award-winning filmmaker Paula Ortiz, who teaches at Barcelona University.

By searching archives and examining letters, speeches and interviews, the pair have recovered the intimate thoughts of Rodríguez, Laforet and Primo de Rivera and put them into the mouths of actors. With the help of their students, who helped produce and subtitle the short films, and the support of the Banco Santander Foundation, the first “filmic capsules” are now available online for free.

Carmen Laforet, who died at the age of 82 in 2004, remains best known for her debut novel Nada, which was published in 1945. The book, published in English for the first time in 2007, is the existentialist tale of an 18-year-old woman trying to negotiate the seedy, cruel and grubby Barcelona of 1939. Photograph: Heritage Image Partnership Ltd/Alamy Stock Photo

The aim, according to Capdevila-Argüelles and Ortiz, was to find a tool “to bring the legacy of the past fully into the present” and put it within easy reach of everyone.

“We didn’t come up with the words that the actors have made their own – they were already written and already there,” says Capdevila-Argüelles, who has also worked to ensure Madrid commemorates a lost generation with a series of plaques of female writers, artists, scientists and thinkers silenced under Franco.

“The project is about taking these legacies that are key to understanding our culture, our politics and our history, and putting them very much in the here and now,” said Capdevila-Argüelles.

Ortiz added: “What’s fascinated me from the beginning of all this is that, while women have obviously contributed half of all history and half of all thought, that’s not even close to being reflected in our culture or in the products of our culture.

“It’s just not there, so we have to go looking for it in those hidden places where women’s thoughts, feelings and ideas have always been kept. Even though they didn’t have the opportunity or the right to have a public voice or presence, they still made use of the tools they had and of their private spaces, be they letters or diaries.”

And that, she adds, is where the real treasures are to be found: “the sexual and reformist work of Hildegart Rodríguez; the plans for statewide organisation you get in Pilar Primo de Rivera; and the deeply poetic and profoundly philosophical creative attitude of Carmen Laforet.”

Rodríguez was the self-described “eugenic daughter” of a mother determined to create a superhuman. In letters to her “spiritual father”, the English sexologist Havelock Ellis, Rodríguez talks of her belief in the urgent need for family planning while also mentioning her ringlets and a “mummy” who never leaves her alone.

Rodríguez was 18 when her mother killed her in 1933, apparently terrified that her preternaturally gifted child was slipping away from her. “I think if we were American, there would already be three films about her,” says Ortiz.

Laforet, who wrote Nada (Nothing) – one of the great Spanish novels of the 20th century – emerges as an author profoundly and painfully unaware of her own worth: “I remain absolutely convinced that this work of mine does not give or take an ounce of spirituality to or from the world, that it is not important to anyone; and I dedicate myself to it knowing of its many defects, enormous plot holes, and lack of moral purpose.”

Hildegart Rodríguez, who exchanged letters with HG Wells and US birth-control campaigner Margaret Sanger, was 16 when she published a controversial book – Did Marx Get it Wrong? – in 1932, a year before her mother shot her dead. She was the subject of a 1977 feature film and a shorter one, in 2011. Photograph: History and Art Collection/Alamy Stock Photo

Then there is Primo de Rivera. In the film, after railing at those who call her a fascist, she points to the work that the Sección Femenina did to improve infant health and the lot of women in post-civil-war Spain.

“If it weren’t for us, Spanish women would be 40 years behind European women,” she says. “If the Sección Femenina hadn’t existed, Spanish women would have had nothing, absolutely nothing, only backwardness, ignorance, submission … and dictatorship.”

Primo de Rivera, who died in 1991, is careful to point out that the section was under her command – not Franco’s – and that it was, as she puts it, her baby: “I gave birth to it, I raised it, I buried it, and no one else was ever in my position.”

She also gives short shrift to what was expected of her as a woman of her era. “I have never been beautiful,” she says, “nor liked wearing makeup or flirting with men. I do not think these necessary in order to feel like a woman. They whispered behind my back; that I looked a mess, that I had not heard of shampoo, that I always dressed as if I were a sexton’s daughter.”

Capdevila-Argüelles and Ortiz are aware of how the inclusion of Primo de Rivera could be viewed in a Spain struggling to come to terms with its past and to break with the post-Franco pact of forgetting.

She lived well into Spain’s post-Franco return to democracy, dying in 1991, and defended her actions and achievements to the end, saying: “Nowadays people say that I was authoritarian, reactionary and, first and foremost, a fascist – as if I had exterminated Jews like Hitler did. They accuse me without wanting to listen … Accusing someone is very easy and very comfortable because those that accuse are automatically free from blame.”

But Capdevila-Argüelles and Ortiz are adamant the project is not an exercise in hagiography. “These pathfinding women were visionaries, but there were also huge paradoxes because it wasn’t easy for any of them to be who they were,” says Capdevila-Argüelles. “We’re trying to show the tensions in their thoughts and in who they were.”