Big Brother knows. You didn’t read all of George Orwell’s novel “Nineteen Eighty-Four” when it was assigned in high school. It’s OK. You’re not alone.

“No one reads the whole thing,” says Duncan Macmillan, laughing. Like many, the British playwright read it around age 15, and recalled it as “a stodgy, dystopian tale of surveillance,” he says.

But then, several years ago, he and fellow Brit Robert Icke decided to co-write and co-direct a stage adaptation of the famed novel. That production, which earned rave reviews in London with a different cast, will open on Broadway on June 22 at the Hudson Theatre. It will star British actor Tom Sturridge as the naive rebel Winston, Olivia Wilde (making her Broadway debut) as the mysterious, seductive Julia, and Reed Birney (who won a Tony Award last year for his moving performance in “The Humans”) as the even more mysterious bureaucrat O’Brien.

In rereading the novel as an adult, and preparing to adapt the story for the stage, Macmillan realized the book is far from stodgy, but provokes a host of questions, which tumble out of him.

“How do we know what’s real? And who do we choose to believe? Who controls the facts we’re exposed to? Or the truth? And if you don’t know what’s true, how can you trust your own thoughts?”

He takes a breath. What he doesn’t say is obvious — all these questions seem as remarkably relevant today as they must’ve been back when Orwell’s book was published in 1949. And this fact is not lost on audience members, who respond in vastly different ways. Some moan. Some shout out. And, yes, some reportedly even faint.

Big Brother would be pleased.

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LEARNING THE VALUE OF LIVE THEATER

The visceral response to the play intrigues Macmillan.

“It’s increasingly hard to get out of our echo chambers, our bubbles,” he says. “But theater can help. There’s something about the experience. It’s communal. We’re sitting with strangers who are all over the political spectrum. But we’re all together. And it’s here where we can wrestle with the gray areas and contradictions of our own beliefs.”

But audiences have done more than wrestle.

“It’s so dependent on what happened in the news, and on Twitter, that day,” he says. “Some nights people laugh. Other nights, they yell out, ‘Resist,’ and others yell back, ‘Shut up!’ And it’s not just a liberal audience,” he adds.

As for the fainting? No one was seriously injured, he assures.

For the record, the show can get a tad gory, but no more so than a bit of Shakespeare or a production of “Medea.”

“At least with the novel, if it gets too intense you can put it down,” says Macmillan. But the play establishes an inescapably tense atmosphere from the moment audiences enter. Before the show begins, a low rumbling permeates the theater. A harbinger of things to come.

STAGE FRIGHTS

For the actors onstage, the audience engagement is exhilarating.

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“The other night, a woman said, ‘Please, please stop this,’ while . . . um . . . not very nice things are happening to me,” says Sturridge.

At one performance, a fight even broke out in the audience and the police were called, Sturridge reports. “Passions run high.”

They certainly do. In one scene, Winston and Julia meet in the woods for a tryst. It starts with the two actors flailing, and handling each other roughly. Sturridge has wound up with a busted nose, Wilde a split lip. Each shrugs it off.

“Who knew historical fiction could be so dangerous?” Wilde says, chuckling. Then she gets serious, noting she’s never in real danger.

“I’m the least experienced theater actor on the stage,” says Wilde, who audiences will recognize from her stints on TV series like “House” and “Vinyl.”

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“I keep talking about this backstage,” she continues. “It’s remarkable how actors in a play take care of each other in a profound way. We keep each other alive out there. And safe. There’s a deep connection we all feel. I’m really very moved by it.”

LIGHTS UP

That sense of connection is something audience members may also feel among themselves, when the action onstage moves to a secret government facility and, yes, the infamous Room 101. No spoilers here, but those who’ve read the book will recall that nothing good ever happens there. As one character pleads, “Shoot me. Cut my throat. Anything, but Room 101.”

At this point, the house lights are brought up, and the audience and actors are all in full view of each other — complicit in the action onstage.

A glance down your row will reveal a sea of humanity — a woman with her hands over her mouth, several others leaning forward in their seats. It feels, in a way, like its own form of immersive theater.

“I goofily enjoy it,” says Sturridge. “When I have a chance to look into people’s eyes, it’s . . . powerful.”

Once again, he says, the responses vary.

“Some people cower,” he says. “The guys often look away. Some — the girls — try to empathize. You see this maternal need to protect in their eyes.”

The fact that this musty old tale — or, at least, that’s how many of us may erroneously remember it — still has the power to evoke such emotion is heartwarming for Macmillan.

“That we’re still talking about these things — surveillance and oligarchy and terrorism, that it’s still so relevant, is terrifying and sad,” says Macmillan. “But for me, as a writer and director, to give Orwell his Broadway debut and bring his work to a wider audience is such a privilege.”

He can’t help but wonder what Orwell, who died less than a year after his novel was published, might think.