Solar wrote her Harry Potter fanfic at the age of 21

La Septima M - The Seventh M - is the first of three books that 23-year-old Chilean journalism student Francisca Solar was contracted to write by publishers Random House, following the online success of her unofficial sixth Harry Potter story, Harry Potter and the Decline of the High Elves.

Launched at the recent Frankfurt Book Fair, La Septima M centres on a mysterious series of suicides amongst young people in the fictional community of Puerto Fake.

"All the things I know about literature, about writing, I learned in the fan fiction world," Solar told BBC World Service's The Word programme.

"I owe it everything."

Online smash

Solar began her writing career when she found she was so disappointed with JK Rowling's fifth Harry Potter book, Harry Potter and the Order of the Phoenix, that she wanted to write her own sequel to it.

The Decline of the High Elves became a massive online smash, generating 80,000 views and positive reviews from Harry Potter fans around the world.

All these people wrote to me about the fanfic and said they liked it more than the official sixth book Reviews of Harry Potter and the Half-Blood Prince

"When I read the fifth book, I was so disappointed - I'm a very critical reader, and I'm a huge fan, so the expectation of this fifth book was great," Solar said.

"I took the principal characters and I did a story that is more rich than Rowling's story, because you can have access to the thoughts and feelings of all of the characters.

"In the Harry Potter saga, you can only have access to Harry's feelings and thoughts. That is a partial view of the Potter universe."

She admitted she had never expected the global response to her work.

"Many people from all around the world have written to me, from the US, from the UK, from Asia," she said.

"All these people wrote to me about the fanfic and said they liked it more than the official sixth book [Harry Potter and the Half-Blood Prince]."

However, the editors at Random House insisted they did not want "another JK Rowling" and wanted something fresh - hence La Septima M, which will itself be followed up by two further books to complete a trilogy.