Michael Morpurgo is standing on a sun-drenched beach, waves lapping at his feet. Clutching his mobile phone, the author walks through the warm Greek sea, the sound of water echoing down the line to a cold and rainy Edinburgh. Jealous, me? Never. Morpurgo has travelled to Greece to finish his new novel, the latest addition to his vast catalogue of young people’s fiction. With over 100 books to his name, an MBE, OBE and a three-year spell as Children’s Laureate, Morpurgo’s place in literary history is assured.

Today he’s talking to me about The Mozart Question, his 2007 novel which has been lifted from page to stage for this year’s Fringe. It’s the third year in a row that his work has visited Edinburgh, with Private Peaceful and Aesop’s Fables garnering five star reviews in 2006 and 2007 respectively. ‘If theatre is done right it can have a massive impact, and in a much shorter time than reading a book,’ he says. ‘For instance, there’s a huge dramatic intensity in Private Peaceful, which takes you four or five hours to read, but you can go through that same experience in an hour. The same with Aesop’s Fables, which can be funny or serious. If the direction is good and the acting is terrific, then the theatre can bring stories to life wonderfully well.’

Audiences for The Mozart Question (as well as those at his two Edinburgh International Book Festival events) would do well to buy tissues along with their Fringe tickets because, as with much of Morpurgo’s work, tears are almost inevitable. By combining factual research on traumatic events with very personal stories, the 61-year-old tugs at even the toughest of heartstrings. ‘The profoundest thing that happens to me is when I get letters from children which don’t just say that they liked the book, but say, “My mother was reading your book to me and she couldn’t finish it because she was crying, so I had to finish it for her.” And that’s what’s so wonderful about literature, because it takes us to places which, emotionally, we haven’t been to before.’

Set in the present day and during World War II, The Mozart Question was inspired by two real-life events. Firstly, the Holocaust and its associated horrors, and secondly a young child that Morpurgo and his wife observed while on holiday in Venice. ‘It was 11 o’clock at night and this five-year-old boy was sitting on a bicycle in his pyjamas, listening to a young man play 17th century Spanish guitar music,’ recalls Morpurgo. ‘And instead of walking away after a bit, which is what children of that age normally do, he was still there half an hour later after we left, completely entranced.’

In Morpurgo’s story, that child grows up to be Paulo Levi, the world’s greatest violinist, but one who refuses to play Mozart. As the story unfolds, we discover that Levi’s parents were survivors of the Nazi concentration camps, with their own particular reason for eschewing Amadeus. ‘I came across the awful truth that in some concentration camps, Jewish musicians were obliged to play music,’ explains Morpurgo. ‘Sometimes it was Bach but most often it was Mozart. And they would serenade prisoners as they arrived at the camps. And I thought if you’d done that, would you ever feel like playing Mozart again?’

Just as Private Peaceful turned the 800,000 young men who died in World War I into a very personal story, The Mozart Question does the same for the Holocaust. Historical facts and figures may paint an overall picture, but for a generation born over 50 years after the event, it can be hard to compute. Which is why Morpurgo’s words pack such a punch, turning a nameless soldier into a son and a statistic into a father.

‘I think children can get a handle on it if it’s personal,’ says Morpurgo. ‘They hear figures like, “six million Jews died in concentration camps”, but what does that mean to a child of today? However, if you focus in on one of those people who died, it then brings it into much sharper focus. So, although this story is about one musician, really it’s the story of all six million.’

The Mozart Question, Assembly Rooms, George Street, 0131 623 3030, 3-25 Aug (not 11), 12.15pm, £11-£12 (£9-£10). Previews 31 Jul-2 Aug, £5; Michael Morpurgo’s Legends, 18 Aug, 4.30pm; The Mozart Question, 19 Aug, 5pm. Both events at Charlotte Square Gardens, 0845 373 5888, £3.50.