Greig, who has also written the book for the new Sam Mendes film musical of Charlie and the Chocolate Factory, researched the project on Utøya Island and in Oslo, visiting the country with the director Ramin Gray three months after the atrocity that saw the lone killer end the lives of 77 people.
Called The Events, the show examines the limits of human empathy and will be premiered this summer at Edinburgh's Traverse Theatre, before it travels to London for a run at the Young Vic.
"I was most interested in how Norwegian society was feeling," said Greig this weekend. "Oslo is not a huge city and everybody pretty much knows everybody else, so almost everyone we spoke to had been affected. Some people asked us not to write or talk about Breivik. I am not at all certain whether we give him a victory by ignoring him or trying to understand him. That is what I wanted to question."
Greig and Gray, who already shared an interest in Norway, spoke to many who had lost friends and relatives. As a result, the writer eventually decided not to name Breivik in the show and to relocate the atrocity to his native Scotland.
His story centres on a woman, described as being "at the centre of the events", who has to try to decide on her response to the impact of a politically and racially motivated mass murder.
'Limits to empathy'
Gray, who commissioned Greig to write the piece for the Actors Touring Company, recalled that on their Norwegian trip they talked to a journalist who revealed that he had been at school with Breivik and was able to give them detailed information.
"We had a lot of angst about whether it was at all right to even do something on this," he said. "It was such a devastating incident, but David wanted to ask whether there are limits to empathy and whether it can even become destructive itself."
Musical theatre has often approached dark subjects. Spring Awakening, a show based on the controversial German novel by Frank Wedekind, deals with teen rape, suicide and abortion, while a recent National Theatre production, London Road, was written in response to the murders of five prostitutes in Ipswich in 2006.
The score for The Events has been composed by John Brown and involves the voices of a community choir. "Choirs seemed to be the right way to represent that basic faith in the group," said Greig. "They are also theatrically interesting because of the Greek and Brechtian traditions of the chorus, and also the chorus lines of musical theatre."
"Breivik's violence was done to an entire society," he added. "I was interested in how people responded. Norway seems to be a poster boy for the liberal West. It represents the Scandinavian social democratic ideal and the attack seemed to be aimed at that."
In proportional terms, said Greig, the Norwegian murders were akin to the 9/11 attacks on New York. "Americans responded one way, and Norway responded with democracy. I wanted to look at whether trying to understand a crime of this nature is really the best way," he said. The writer said he hoped the show would give the audience an experience almost the opposite of a Greek tragedy, which follows a character's thirst for revenge. "Instead, this woman searches for understanding – but I wanted to question that impulse too," he said.
The playwright's earlier work Dunsinane was recently produced for the Hampstead Theatre by the Royal Shakespeare Company and he is working on plays for the National Theatre of Scotland and the Royal Court in London. He hopes The Events will make audiences wonder whether a mass murderer such as Osama bin Laden is so different to a lone killer such as Breivik – and that the show will make a wider connection, to the horrors of Dunblane, Hungerford and Sandy Hook elementary school. – Guardian News and Media 2013