By the end, they may be tempted to throw those phones out the window.
James Graham's exciting, interactive and alarming drama suggests that our smartphones and computers know us better than we know ourselves. The play asks whether privacy is dead in an era when millions share their innermost thoughts on social media, mobile phones act as electronic trackers and government snoops hoover up vast amounts of data on their citizens.
Graham insists the play is not arguing "that we should all dump our iPhones in the dustbin." Despite months of eye-opening research, he still has a smartphone and a Twitter account.
"We wanted to say, look, a lot of this stuff is amazing, but we have to keep constantly checking in and going, is the balance right?" he said. "The amount we share ... has changed radically in the past five years in a way I think it hasn't in the past 500 years."
The play, which opened this week at London's Donmar Warehouse, follows a fictional writer and a director — "better-looking, thinner, younger versions of us," quips the play's real director, Josie Rourke — as they explore the power of the Internet and the meaning of identity in an online age.
Graham — a 31-year-old wunderkind whose last play, "This House," made backroom British politics in the 1970s unexpectedly thrilling — conducted 60 hours of interviews with dozens of researchers, politicians, civil liberties activists and spies.
A cast of six plays everyone from the former head of British spy agency GCHQ to the inventor of the supermarket loyalty card and Cambridge University academics who say they can infer everything from political views to sexual orientation from an individual's Facebook "likes."
Former National Security Agency contractor Edward Snowden appears, too, as do the Guardian newspaper journalists who published his leaked documents revealing details of U.S. spies' ability to snoop on vast amounts of electronic communications.
But what could have been just an illustrated lecture is elevated by Rourke's snappy staging, deft performances and innovative use of audience participation.
Before long, members of the audience are taking selfies and emailing them in. Soon theatergoers' home addresses, occupations and much more are being beamed on big screens to the audience.
Fittingly enough, Graham and Rourke hope viewers will keep the details of the show's more dramatic revelations private. But on opening night, some audience members audibly gasped at how much their electronic devices disclosed.
During intermission, the theater was full of people hastily changing the privacy settings on their phones. That's music to the ears of the writer and the director.
"Part of the ambition of the show is to have people understand what the relationship is between them and their data ... be that Facebook, Google or the security services," Rourke said. "What are they taking, what am I giving, what do I want, what am I happy with?"
"Privacy" is the latest hit for the Donmar, which has an influence far bigger than its 270 seats and a strong record of attracting younger theatergoers. The company recently had fans lining up around the block to see "Thor" star Tom Hiddleston in Shakespeare's grueling tragedy "Coriolanus."
Graham said his goal with "Privacy" was to make a complex issue feel urgent by making it "about people's shopping and about people's relationships and about people's love life and about people's feelings, about people's sexuality, about people's politics."
"If we can do that and also have people leave at 10 o'clock at night going 'I really enjoyed myself at the theater,' then that for me is the pure reason why I became a writer," he said.
"Privacy" runs at the Donmar Warehouse until May 31.
Follow Jill Lawless at http://Twitter.com/JillLawless