Before he appeared on television contest Sing! China, Nathan Hartono was singing about ancient China for an original Singaporean musical.

Hartono, 25, will be starring in The Great Wall: One Woman's Journey, which runs from July 14 to 30 at the Drama Centre Theatre.

The musical is a five-year labour of love from a creative team that includes Singaporean playwright Jean Tay and producer Grace Low of the brand-new Glowtape Productions.

"Every day, I still think I'm crazy for doing this," says Low, 36, who set up the company just for this musical. It has cost an estimated $800,000 to produce and was helped by a production grant from the National Arts Council.

The creative team includes Australian director Darren Yap, who directed the musicals Mamma Mia! (2004) and Miss Saigon (2001) in Singapore.

Music is by British composer David Shrubsole, who composed for the National Gallery Singapore's opening festival and worked with Yap and playwright Tay on the Singapore Repertory Theatre's Pinocchio The Musical in 2010.

The Great Wall is based on the legend of Meng Jiang Nu, whose husband died while working on the construction of the Great Wall of China under the command of the Emperor. Her grieving tears cracked the Great Wall and forced the Emperor to acknowledge her loss.

Tay, 43, said that image had always resonated powerfully with her. It came to mind during the political protests of the Arab Spring in 2010, when she, Yap and Shrubsole first worked together. Low was also with the Singapore Repertory Theatre at the time and the four decided to do another musical together. Low has years of backstage experience, including as a stage manager for TheatreWorks productions, so she knew good things take time to develop. She was not keen to rush the process.

She says: "The one thing I find lacking in Singapore is the time we take to develop new work. I'm not going to fall into the trap of 'I must bring out a show by this date'."

In 2012, as they had their first workshop, Low asked Hartono, to record a song from the work in progress. He liked the music so much that when she asked him to be in the cast, he agreed.

"It was because of the music that I agreed to do this. I hadn't even read the script," he said. "The music is pretty dope.

"Everyone's going to assume it's something that's full of erhu and pipa, but it doesn't sound like that. "

Shrubsole, 44, points out that erhu and pipa were not around at the time the Great Wall was built. Chinese musical instruments of that time included gongs and a dulcimer, not much else.

Asked to describe the score he has come up with, he laughs. "What I've been trying to do is to not make it sound like the archetypes of Western music," he says. "It's easy. The story naturally sings."

Hartono plays Fan Qi Liang, the husband of Meng Jiang Nu. The key role is played by Dutch-Korean actress Na-Young Jeon, who played Fantine in the West End revival of Les Miserables in 2013 and 2014. Singaporean singer-actor George Chan plays the Emperor.

The Great Wall was mooted during the time the Arab Spring showed a population standing up to authority. The team is conscious it will show now in a time post-Brexit, when populations are building metaphorical walls against outsiders.

Director Yap, 49, says: "The musical is about symbolic and metaphorical walls. What is a wall and how do we build walls around us?"

He thinks the musical will appeal to audiences at different levels. After all, it has kept him hooked for more than five years.

"It's very rare to see a female character being strong and standing up to authority in musicals," he says. "There has been a lot of curiosity about the next Asian musical hit since Miss Saigon and this could be it."