It is, quite simply, spellbinding: The Show That Lived Up to Expectations — and Then Some. Three years after J. K. Rowling announced her boy wizard would hit the stage, “Harry Potter and the Cursed Child” — no mere rehash, but a whole new chapter — proves a proper theatrical blockbuster. Not just at the box office, but onstage as well: a captivating story given a spectacular staging and — Rowling’s specialty — a big, big heart. Twenty years ago, Harry Potter turned a generation onto reading. “The Cursed Child” could do the same for theater.

Its secret is simple: Rowling’s fantastical world is realized not with high-tech wizardry, but through the rough magic of theater. Broomsticks hop into their owners’ hands. Wands spit green jets of fire, blasting wizards ten feet into the air. Bodies vanish, balloon and transfigure. Ears shoot steam. Objects levitate.

Director John Tiffany’s staging is full of tiny impossibilities, but it’s big on imagination too. Suitcases spring into shape as the Hogwarts Express, and two shifting staircases make a maze of school corridors. Huge iron arches, the ribs of the roof at Kings Cross station, slide in to become the Forbidden Forest. Even scenes changes proceed with the swish of a cloak. The whole thing seems motored by magic.

Rowling’s sequel picks up where the books left off, with that coda at Kings Cross, 19 years on, as Harry sees his second son, Albus Severus Potter, off to Hogwarts for the first time. He is, as the book suggests, an anxious kid, nervous about leaving home, uncomfortable with attention and scared of being sorted into Slytherin.

If the originals showed one side of adolescence, “The Cursed Child” presents another — not the golden boy fighting for good, but the misfit battling with himself. Sam Clemmett’s Albus is a meek young thing, forever in his father’s shadow and preferring Hogwarts’ dark corners to its limelight. He finds an unlikely friend in Scorpius Malfoy, Draco’s son: geeky, gawky and, in Anthony Boyle’s hands, all fingers and thumbs. The more the pair try to ingratiate themselves with their peers, the more they end up isolated.

It’s the friendship of two bullied boys bound together, and it’s a beautiful, tender thing. The script by Jack Thorne (“Skins,” “Shameless”) recognizes that rejection breeds resentment, and outsiders stew into outcasts. No one’s born a villain, nor sees themselves as such, and where the books gave us stock baddies, “Cursed Child” fleshes them out. Albus and Scorpius only ever try to make good, but their efforts tend to lead to bad.

This is, however, still Harry’s story as much as his son’s, and if, 20 years ago, Rowling shepherded a generation through their teenage years, now she provides parenting lessons. An orphan abused by his foster family, Jamie Parker’s Harry struggles with his son. Their conversations always come back to him; their relationship is stern and serious, never playful or affectionate. The Boy That Lived has become The Man That Frowns — his hero complex is a burden and his childhood a barrier to letting others in. Parker’s superb. When he folds his arms, he seems to hug himself. His own frustrations rebound on his son.

Rowling has found a neat way to revisit her original, allowing for both novelty and nostalgia. Without giving those secrets away, her plot has shades of fan-fiction to it, revealing the past anew and prodding at its possibilities. It’s built for aficionados, of course, and while flashbacks and (clunky) exposition fill in the key plot points, you do need a knowledge of the world itself, from floo networks to Dementors’ Kisses.

Where it retreads old ground, the “Cursed Child” sometimes stutters. Familiar faces make welcome returns, but they’re pale imitations of their old selves. Theater butts up against its limitations too: the evils that seemed so vivid in your head or on screen stray into high camp on stage. That holds back Part Two of this five-hour-plus epic. When plot kicks in, it doesn’t yield the same wonder as the world that’s pulled together in Part One.

The show is far better when it moves things on. As adults, Ron and Hermione are the same as ever. Noma Dumezweni adds a cool authority to the latter’s racing mind, and Paul Thornley finds humor in the old Weasley haplessness. It’s Boyle, though, who really stands out, and his Scorpius is bound to be a new fan favorite, a lovable geek with wits as quick as his voice is screechy.

Beneath the surface, “Cursed Child” is absolutely contemporary. It shows a generation that has known only peace and certainty on the cusp of chaos; its villain isn’t an overlord with an army at hand, but a lone terrorist acting in and out of isolation. Even run by good people, the Ministry of Magic makes mistakes, and the Marauder’s Map, once a mischief maker’s friend, has become a surveillance tool. The answer this time is not solo heroics but collective action.

That’s true of the show itself. Its every element pulls together. Christine Jones’s shapeshifting space, all oak paneling and wrought iron, seems to ripple with Finn Ross’s projections. Jamie Harrison’s illusions, sleight of hand and misdirection would be nothing without Neil Austin’s exquisite lighting. Steven Hoggett’s movement makes the most of Katrina Lindsay’s costumes. It’s total theater. And, yep, it’s magic.

West End Review: ‘Harry Potter and the Cursed Child’

Palace Theater, London; 1,400 seats; £65 (£130 for both parts), $85 ($170) top. Reviewed July 23rd, 2016. Running time: <strong>5 HOURS, 15 MIN.</strong>

  • Production: A Sonia Friedman and Colin Callender production of two play in two acts by J.K. Rowling, John Tiffany and Jack Thorne.
  • Crew: Original story by J.K. Rowling, Jack Thorne and John Tiffany; Script by Jack Thorne; Directed by John Tiffany; Set design, Christine Jones; costume design, Katrina Lindsay; Composer, Imogen Heap; lighting, Neil Austin; sound, Gareth Fry; Special Effects, Jeremy Chernick; Illusions and Magic, Jamie Harrison; Musical Supervisor, Martin Lowe; Casting, Julia Horan.
  • Cast: Nicola Alexis, Jeremy Ang Jones, Helen Aluko, Rosemary Annabella, Annabel Baldwin, Jack Bennett, Paul Bentall, Anthony Boyle, Zoe Brough, Sam Clemmett, Morag Cross, Noma Dumezweni, Christina Fray, Claudia Grant, James Howard, Christiana Hutchings, Lowri James, Martin Johnston, Chris Jarman, Alfred Jones, Chipo Kureya, James Le Lacheur, Helena Lymbery, Tom Mackley, Barry McCarthy, Sandy McDade, Andrew McDoanld, Adam McNamara, Poppy Miller, Tom Milligan, Jack North, Jamie Parker, Alex Price, Stuart Ramsay, Ewan Rutherford, Nuno Silva, Cherrelle Skeete, Esther Smith, Nathaniel Smith, Dylan Standen, Paul Thornley, Joshua Wyatt.