My novel, Ghost Variations, is a fictionalised account of how the Violin Concerto by Robert Schumann came to light in Nazi Germany in the 1930s, 80 years after the composer's death.

The true story, though, is stranger than fiction. And finding the right format for that story, and a means to disseminate it, was suitably strange, too.

As Joseph Goebbels well knew, nothing is ever just a piece of music. When the Nazis' Ministry for Public Enlightenment and Propaganda overrode a 100-year embargo upon this long-suppressed work, they had a specific reason for doing so. Having banned music by Jewish composers, including the popular Violin Concerto by Felix Mendelssohn, they needed a replacement to present to a disgruntled public. What could be better than Schumann? A great German violin concerto by a great German, Aryan, composer. Or so they thought.

The situation, and the music, was more complicated than that. This concerto was Schumann's last orchestral work, completed in October 1853. A few months afterwards, the composer suffered a nervous breakdown and attempted suicide - the culmination of long mental instability and, probably, tertiary syphilis. He spent his last years in an asylum, where he died in July 1856.

Schumann had intended the piece for Joseph Joachim, then a celebrated young Jewish Hungarian violinist, through whom Schumann and his wife, Clara, first met the youthful Johannes Brahms. Joachim, though, had doubts about the concerto's quality. Clara, too, feared it betrayed signs of her husband's final illness and she therefore refused to have it published. Joachim kept the manuscript; later his heirs deposited it in the Prussian State Library, Berlin, with instructions that it must not be played until 100 years after Schumann's death.

Joachim had three talented great-nieces, the d'Arányi sisters from Budapest, who all settled in London. The eldest was his pupil: a strong, rigorous performer who enjoyed a flourishing career under her married name, Adila Fachiri. Hortense, the pianist, gave up performing after marriage. But the youngest, Jelly (pronounced Yelly), became one of the most significant violinists of her time, not least because so many composers created new works for her, including Bartók, Ravel, Vaughan Williams, Ethel Smyth and Holst. The Australian composer Frederick Septimus Kelly, whom she had hoped to marry, wrote her a sonata before he was killed at the Battle of the Somme in 1916.

In 1933, Jelly d'Arányi, then aged 40, claimed to have received a communication via a "glass game" - an Ouija board séance - purporting to be from the spirit of Robert Schumann, asking her to find and perform his long-unplayed concerto.

She was backed up by her sister Adila Fachiri, who was now a psychic "sensitive", and who subsequently helped the Swedish Ambassador, Baron Erik Palmstierna, to pen three books based on spirit messages she had channelled.

Many explanations for these events have been volunteered, but I've spoken to people who knew the sisters and everyone has insisted that the two believed in the "messages" wholeheartedly. Unfortunately, nothing could have been more calculated to work against them when the story went public in September 1937.

D'Arányi enlisted the help of the music publishers B Schott und Söhne from Mainz, the publishers of her old friend, the musicologist and composer Donald Francis Tovey. But it was only after various personnel changes at the Prussian State Library and the Reichsmusikkammer that matters gathered pace. D'Arányi's enquiries had alerted the authorities to the fact that something valuable was lurking in that archive.

Schotts had a crucial role in all this. Indeed, the mercurial activities of Willy Strecker, head of the firm, almost beggar belief: think of Jerry the mouse dancing about under Tom the cat's nose, only to whisk away, leaving him swiping to no avail. Strecker not only drafted in Paul Hindemith, a composer who was persona non grata with the Nazi regime, to rework some aspects of the concerto, but also sent a photostat to the young Jewish superstar violinist Yehudi Menuhin, who was then living in California.

Menuhin fell in love with the work and longed to give the modern premiere himself.

To deal with Menuhin and d'Arányi, the Nazis formalised a strict order of performance, placing their own candidate - the German violinist Georg Kulenkampff - first; Menuhin second; and d'Arányi third.

D'Arányi,whose Jewish heritage was clear, since she was famously related to Joachim, had to be content with the UK premiere; Menuhin, to his choleric and controlling father's fury, was accorded the American one.

The German authorities appeared to try, twice, to derail the competitors by moving Kulenkampff's concert date, but eventually staged the modern premiere in November 1937 in their popular Kraft durch Freude (Strength through Joy) concerts: heavily stage-managed, preceded by a speech by Goebbels, and presented in front of Hitler.

In yet another twist, a performance of the Schumann also took place in Jerusalem, before d'Arányi's. The Chamber Orchestra of the Palestine Broadcasting Service, the forerunner of the Jerusalem Symphony Orchestra, performed it in January 1938 with its leader, Sasha Parnes, as soloist.

Controversy dogged d'Arányi's battle for the concerto. The story of the spirit messages caused some public hysteria when it hit the press, and her health and ability to play the violin - already suffering under a litany of injuries - began to be affected.

Yet, without her investigation, the Schumann Violin Concerto might never have emerged. It may not have been technically "lost" but it still needed to be found.

This bizarre story seemed to me a book crying out to be written. But I had to find the right path, because it fitted few conventional channels. "Fiction or non-fiction," ask most publishing professionals; the answer "a bit of both" is rarely welcomed. Moreover, to judge from my experience to date, unless you happen to be Julian Barnes or Ian McEwan, utter the words "classical music" to most UK book publishers and you won't see them for dust.

Enter Unbound, an innovative, new-model publisher that crowd-funds its books and actually likes projects beyond conventional niches. After several fine journalists recommended the firm, I plucked up courage to run Ghost Variations by them. To my delight, they took it. But the next challenge was the crowd-funding. I'd never crowd-funded anything before; the learning curve went over the hills and far away.

It's tricky to get right as the British traditionally loathe "self-promotion" and people asking for money, and crowd-funding involves both. Therefore, occasionally, you're greeted with a type of Victorian disdain that would once have been reserved for those "in trade".

However, Unbound's model allows you to prove that there is a market for your project. You build a community in advance, offering creative rewards for your supporters, for instance, "character sponsorships", a group outing to a concert and a playlist of music to accompany the story.

To my amazement, I made the target in 12 days.

But it's not only the financial benefits for the book that proved so heart-warming, it's the moral support. In conventional publishing, you work with your editors but not your readers. With Unbound, the readers are part of the process - after all, the book is ultimately for them to enjoy.

If my book didn't fit conventional channels, neither did the Schumann Violin Concerto itself.

A fragile, searching and sometimes sombre work, it did not serve Goebbels' tub-thumping purposes. Written on the brink of Schumann's breakdown, the concerto surfaced just as the pre-war world was on a similar brink, about to plunge over the edge. To some extent, its resurrection proved it an insane work for an insane time.

But the final movement is a Polonaise, a dance that in the hands of Chopin and his friends, Schumann included, often became a symbol of Polish nationalism. About 18 months after Jelly Aranyi performed the concerto in London, Hitler invaded Poland. Yet the Polonaise ultimately stands triumphant. It is the music that lasts to this day. Jelly and Schumann - spirits or none - have had the last laugh.

'Ghost Variations', by Jessica Duchen, will be published by Unbound on 1 September 2016.