NEW YORK • About half an hour into Cory Doctorow's discussion of his new science-fiction novel, Walkaway, at the New York Public Library last week, the man interviewing him suddenly froze in midsentence.

The crowd murmured uncomfortably as technicians rushed to the stage to fix the video feed, which beamed a frozen image of Edward Snowden, who was about 7,500km away in Moscow, onto two large screens.

"Oh, there's the NSA," Doctorow joked when the video stalled. "Ed warned us this might happen and said we should just make a joke about the NSA and wait for him to come back."

Snowden, a former contractor for the National Security Agency (NSA) who leaked a trove of classified documents that revealed the agency's vast surveillance operation against hundreds of millions of United States citizens and others, has become something of a fugitive hero and pop-culture icon.

He has been featured in video games and a graphic novel and is the subject of an Academy Award- winning documentary, Citizenfour (2014), as well as a 2016 feature film directed by Oliver Stone, Snowden.

He appeared, via video, in a play with Daniel Radcliffe at New York's Public Theater called Privacy. There is also an Edward Snowden action figure.

But it was unusual for Snowden to make an appearance at a New York literary event, where he acted as the interlocutor.

"Normally, I don't ask the questions," he said at the beginning of the discussion.

He proceeded to ask a lot of them, pressing Doctorow about copyright law, scarcity and abundance, and other economic and political themes in the novel. He also asked the author whether he intended his book to be an optimistic or pessimistic vision of the future.

"As a science-fiction writer, I'm keenly aware we have no claim to predicting the future," Doctorow said. "If the future were predictable, I don't know why I'd bother getting out of bed."

The event, cheerfully titled Dystopia, Apocalypse And Other Sunny Futures, went remarkably smoothly, considering that Snowden was several time zones away - until it did not.

The discussion ranged from writer Ayn Rand to the predictions of economist John Maynard Keynes to the minimalist philosophy of the Japanese tidying guru Marie Kondo.

All of these disparate subjects, somehow, seemed relevant to Doctorow's novel. Walkaway takes place in a futuristic Canada after the collapse of modern society, when wealth gets concentrated in the hands of the ultra-rich and the less fortunate scrape by in desolate cities that have been gutted by industrial flight.

But the setting is not as bleak as it first seems. Communities of unemployed drifters spring up. In a world with 3D printers, abundant sources of food and mobile fabricators, the people can make anything they need.

Having Snowden act as the interviewer was a brilliant marketing tactic - the packed auditorium erupted into cheers when his face first appeared on the screens flanking the stage - but it also made philosophical sense.

Some of Doctorow's earlier novels feature rebellious hacker heroes who take on shadowy corporations and tyrannical government agencies and fight the erosion of civil liberties.

And Doctorow knew that Snowden was a fan of his work from watching the documentary Citizenfour (in one scene, Snowden stands in his hotel room next to a table that holds a copy of Doctorow's novel Homeland, which features a hacktivist protagonist who is deciding whether to leak incriminating government documents).

So when his new novel was coming out, he tweeted Snowden and asked if he would consider blurbing it. Snowden enthusiastically agreed.

Just before his video feed faltered, Snowden was speaking passionately about freedom and American values.

"This is a country that, many people forget, is born from an act of treason," he said. "We were all rebels willing to risk the rope to create something that was less ordered and more free."

Moments later, as he was talking about how the government's surveillance of its citizens' electronic communications violates the Constitution, he was cut off.

Doctorow improvised for a bit and Mr Paul Holdengraber, director of the library's "Live" programmes, jumped in to ask questions. About 30 minutes later, the video feed was restored and Snowden and Doctorow resumed their conversation.

"It is amazing that a technical problem, which never seems to happen, mysteriously pops up when we start talking about the sensitive political things being born from treason," Snowden said.

"And this really brings us to the central point that we get to when it's past three in the morning in Moscow - the things nobody wants you to talk about."

NYTIMES