What if Nina Simone hadn’t died when she did? The jazz singer would have been 83 years old this year, and chances are, if she was paying attention to the news, she’d be mad as hell and ready, as she once said, to ‘burn buildings’.

“I try and imagine if she was around now,” muses Apphia Campbell, a Florida born, now Edinburgh-based singer who has written a play about the blues legend turned black rights activist, who died in 2003.

“Would she be right back up there, singing those protest songs? Maybe she’d change the words of ‘Mississippi Goddam’ and be singing ‘Texas Goddam’ for 2015 instead!

“To hear her singing those civil rights songs back in the 60s, then seeing that forty or so years later we’ve not really moved on, there’s something incredibly sad about that.”

Campbell’s one-woman play, Black is the Color Of My Voice will return to the Edinburgh Fringe this year, alongside a new sister show, Nina Simone: Soul Sessions, where Campbell sings songs from Simone’s broad back catalogue, including ‘Sinner Man’, ‘Feeling Good’ and ‘My Baby Just Cares For Me’.

Campbell’s not the only one sensing a fresh thirst for the story and songs of Nina Simone. Ruth Rogers-Wright will be starring in another Fringe play, Nina Simone Black Diva Power over at the New Town Theatre, barely a month after Netflix released the documentary, What Happened, Miss Simone?, a collection of rare footage and interviews with her family.

“Nina Simone's brilliance would forever change the musical landscape and yet she never fully got her due,” explains documentary director, Liz Garbus, chatting to The Herald from Pasadena, Los Angeles. “She had been a very popular singer during the 50s, but she never compromised. After songs like ‘Backlash Blues’ and ‘Mississippi Goddam’, she was essentially blacklisted. They were considered too radical, and seen as commercial suicide. Some people gave their life for the black rights struggle, but it’s important not to overlook the price others paid too.”

Garbus’ documentary required a ‘worldwide scavenger hunt’ to find audio tapes, interviews, family confessions and diaries that would help trace Simone’s life. Originally a classically trained pianist, she became a jazz bar diva and latterly, an icon for black power. She became friends with American activists Malcolm X and Martin Luther King, as well as African activists including South African singer Miriam Makeba, who encouraged Simone to relocate to Liberia, where she lived in self-imposed exile for two years.

“She struggled against demons from both within and without,” says Garbus. “Her life was both a reflection of the legacy of racism in America as well as an extraordinary example of the power a righteous voice can bring to bear against even the most wicked historical legacies,” says Garbus.

For Campbell, a singer who keeps getting mistaken for Simone on her publicity posters for Black is the Color of My Voice, it was Simone’s struggle as a woman, and a musician, that seemed particularly fascinating.

“She was a dark character, someone who went through tumultuous times, with bouts of violence and depression, but through them she was always trying to find her voice - was it educated enough? Was it African enough? Was it real enough? Watching YouTube videos of her, I noticed how much her speaking voice, as well as her singing voice could change.”

Simone described her own voice as having the ability to change from ‘gravel’ to ‘coffee and cream’, but for Rogers-Wright, what was always consistent was the emotion she poured in.

‘Most singers don’t take that chance when they perform, but she dared to experiment, to say what she thought, to take you on an adventure of the senses, to show real depth and beauty, and the results were often incredible.”

In Black Diva Power, the story focuses on Simone’s friendship with Lorraine Hansberry – the playwright and black activist who encouraged Simone to become involved in the civil rights movement. Hansberry, who died from cancer, aged 34, urged Simone to carry on her legacy after her death, and Simone’s top ten hit ‘To Be Young, Gifted and Black’ was inspired by Hansberry’s writing, which had been turned into a Broadway play of the same name the year before.

Both Campbell and Rogers-Wright admit they find Simone an intimidating figure to portray on stage. For Campbell, she has created a fictional character, Mena Bordeaux, inspired by the real-life spiritual cleansing that Simone embarked on following her father’s death, where she isolated herself for three days without cigarettes, alcohol, or access to the outside world.

Rogers-Wright saw Simone perform several times in London and was mesmerised, although scared off approaching her outside the venues because she was arguing or agitated each time.

“Nina believed she was the reincarnation of Queen Nefertiti, and sometimes, when you hear her sing in that emphatic way of hers, or even telling her crowd to shut up, you think, maybe she was on to something!

“Her music had a transformative power, it took her to a higher place, somewhere beyond even her shittiest behaviour. This show is a reminder to new and old fans that you can be a strong spirit, fight for what means the world to you, and that’s when unique things happen.”

Black is the Color of My Voice, Gilded Balloon, Wed 5--Mon 31 Aug, 1.15pm, £9.50-£10.50 (£6--£9.50); Nina Simone: Soul Sessions, Assembly Checkpoint, Thu 6--Sun 30 Aug, 8.50pm, £10--£13.50; Nina Simone Black Diva Power, New Town Theatre, Thu 6--Sun 30 Aug, 7.45pm, £7-£14 (£8--£12).