Warren Fitzgerald is a busy man. The East Barnet resident is busy promoting his latest novel, Tying Down the Sun, which is based on his travels to Colombia; he’s writing the book to accompany the documentary he has just made about a community living on a rubbish dump in Nicaragua; he’s got another novel on the boil which was inspired by a trip to Nigeria; and he’s also hoping to get out another book before the end of the year, the sequel to his acclaimed first novel The Go-Away Bird, set during the 1994 Rwandan genocide, which he researched extensively in that country.

“I’m in Barnet at the moment, nowhere exotic,“ laughs the 41-year-old, who worked as a carer for children with special needs until he got a publishing deal with Harper Collins for The Go-Away Bird in 2010, which allowed him to spend more time on his travelling and writing.

The idea for Tying Down the Sun came from a six-day trek through the Sierra Nevada jungles in Colombia, to get to the Ciudad Perida (Lost City) of Teyuna, an Inca site.

“There were ten of us and a guide and a donkey carrying our food,“ remembers Warren. “We had to wade through rivers and cross ravines, it was quite hardcore. It turned out that our guide was a former guerrilla, he was personally involved in drug trafficking – many of the people involved in the tourist industry in Colombia used to be guerrillas, but they’ve realised there’s more money, and a safer income, in tourism than in drugs.

“Also, when we were doing the trek, I heard that a number of tourists had been kidnapped there, by these leftwing guerrillas trying to draw attention to what they thought were abuses indigenous people were undergoing, and that really sparked my imagination.“

Warren played with the facts of the true story of the eight kidnapped tourists and decided to make one of the guerrillas a girl child soldier, an issue that is very important to him, to create Tying Down the Sun, which tells the story of Sarah, a university graduate backpacking around the world, and Luz, a young Amazonian girl who is one of her kidnappers.

It’s a story about hostages and kidnappers, adults and children, asking which is which.

“It’s a very common thing all over the world, child soldiers, but in Colombia particularly,“ says Warren, “and 50 per cent of child soldiers there are girls.

“I’m very interested in the idea of what makes a child and what makes an adult. When we get to 18, suddenly we’re adults, but in one of the Amazonian villages I visited, a girl is an adult when she has her first period and she then has to go through all sorts of harrowing rites of passage to finish that journey into adulthood.

"In the book, Luz is facing being painted blue and having her hair ripped out by her family. All around the world there are different ideas as to when you become an adult.“