The cast of "Harry Potter and the Cursed Child" at...

The cast of "Harry Potter and the Cursed Child" at the Lyric Theatre. From left, Paul Thornley as Ron Weasley, Noma Dumezweni as Hermione, Jamie Parker as Harry, Sam Clemmett as Albus Potter, Poppy Miller as Ginny, Alex Price as Draco Malfoy and Anthony Boyle as Scorpius Malfoy. Credit: Charlie Gray

Any Harry Potter fan knows that drinking Polyjuice Potion temporarily turns one character into another — but to see that magic done live on a Broadway stage, well, let’s just say that is only one of the times that the audience bursts into spontaneous applause during “Harry Potter and the Cursed Child.”

That’s the thing about Broadway compared with London’s West End, where the play originated. In London, the audiences have a lot more decorum, says Anthony Boyle, who plays Scorpius Malfoy, the teenage son of wizard Draco Malfoy. “In America people just go mental. They’re a lot more vocal,” he says. “They’re really enthusiastic.”

And not just for the moments when literal magic happens.

“Some of my favorite scenes are the ones where magic happens between the actors,” says director John Tiffany. “The scene when Harry tries to give Albus the blanket that he arrived at the Dursleys wrapped in I think is incredible. That gets a huge gasp because of what he says to Albus. It’s a form of magic. But it’s magic through two actors being brilliant.”

HEART OF THE STORY

“Harry Potter and the Cursed Child,” which has been in previews at Manhattan’s Lyric Theatre since March 16, officially opens on April 22. It unfolds in more than five hours and in two parts — either on two nights, or in afternoon and evening sessions. It’s already broken the record for the highest single-week gross reported by a nonmusical in Broadway history. Audiences are drawn by reports of wand battles, moving staircases, time travel, talking portraits — and their love of the Harry Potter universe.

The theater has been renovated for the show; the carpeting features the H imprint from the Hogwarts School of Witchcraft and Wizardry and some walls are decorated with protective Patronuses formed from lines of dialogue. Seven of the British actors who had been playing their parts since the show debuted in London during the summer of 2016 have traveled to New York to continue in the roles of Harry Potter, Ron Weasley, Hermione Granger, Ginny Weasley, Draco Malfoy, Albus Severus Potter and Scorpius Malfoy.

The play begins 19 years after the last book in the series left off; Hermione is now Minister for Magic and Harry is the Head of the Department of Magical Law Enforcement. Their children are headed to Hogwarts. The older generation is struggling with being parents, and the new generation with something tougher: growing up.

The relationship between Albus Severus — Harry’s middle child — and Scorpius forms the heart of the story. It’s a friendship fans wouldn’t expect given the heated history between the Potter and Malfoy families. When Boyle walks onstage, it’s immediately obvious what family he belongs to given the unruly white wig he wears — he knows what the audience is expecting.

SCARY MOMENTS

“He has to deal with his father’s past crimes, the stigma of having that name and that hair, walking through Hogwarts’ gates basically as the son of the Antichrist,” Boyle says. “I think people have the idea he’s going to be evil, there’s going to be some sort of evil streak in him. Then he begins to speak and it becomes apparent there’s not a bad bone in his body.”

And fans wanting Albus Severus to live up to Harry’s legacy may initially be disappointed. “It becomes a huge burden for him,” Sam Clemmett says of the tortured character he plays. Albus isn’t so great at spells, and he frankly stinks at Quidditch. Scorpius and Albus bond over the fact that both are outcasts who have been bullied by their peers. “They’re sort of the black sheep within their families. When things get really bad within the story, they find each other,” Clemmett says.

And things do get really bad — Harry’s-scar-hurts bad. In fact, the show isn’t meant for the youngest kids; much of the current audience is in their 20s, people who grew up with the books and movies, Tiffany says. “We’ve said the age group is 9 3⁄4,” he says, alluding to the number also used as the train platform where the Hogwarts Express originates. “People are bringing people younger than that. And they’re being surprised when they start crying. There are some scary moments.”

‘DAUNTING TASK’

In addition to learning their lines, the actors had to master the magic, and there’s plenty of it. The #keepthesecrets campaign that began in London continues here in New York; ushers distribute buttons at the end of the performances with the hashtag, and public relations people stand ready to cast a Stupefy stunning spell on any reporter about to give too much away.

Anyone who really wants spoilers can easily find them with an online search, or they can read the book of the same name that will reveal the plot in detail. But the show isn’t about to help anyone figure out exactly how the magic tricks are pulled off on stage. Jamie Harrison, who is in charge of illusions and magic, is off limits to the press. And Boyle, for instance, has become a member of the Magic Circle, a British organization whose members give their word not to disclose secrets to anyone who isn’t a fellow magician.

But the young actors will say this: Tackling the tricks in addition to learning their lines was a challenge.

“Oh God, yes, absolutely,” Clemmett says. “The learning of magic was quite a bit of a daunting task for me. I’d never done magic in my life.”

In addition to those demands was the pressure of creating a second generation as beloved as the first. “The adults have got seven books to go on. People have already fallen in love with the golden trio,” Clemmett says, referring to Harry, Ron and Hermione. That wasn’t the case for him and Boyle. “You’ve got a blank canvas and you can paint away as you’d like to. That’s really exciting as an actor, but also really daunting.”

Judging by the reaction of fans who wait to greet the actors at the stage door at the end of each show, they’ve accomplished the goal. “There is a line of people going down the block on 43rd,” Clemmett says. “There are massive cheers every night when we walk out.”

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