John Lithgow is superb as Roald Dahl in Broadway show about his revolting anti-Semitism

A couple of words are nowhere to be found in the title of the new Broadway play “Giant,” about children’s author Roald Dahl — namely “friendly” and “peach.”

By the bitter end, it’s clear why. Because this Dahl, viciously played by the superb John Lithgow, is no peach. A peach pit, more like.

Mark Rosenblatt’s meaty debate-drama, which opened Monday night at the Music Box Theatre, shows a much uglier side of the clever mind behind “Matilda,” “Charlie and the Chocolate Factory,” “The BFG [Big Friendly Giant]” and “James and the Giant Peach”: that he was a raging, self-described anti-Semite.

Directed by Nick Hytner, “Giant” fictionalizes, sometimes joltingly, the dangerous moment in the 1980s when the literary titan, whose books are touchstones of childhoods the world over, threw his bigotry out into the open and faced the consequences.

Staunch Dahl bets he’s too gigantic to fail.

His petrified employers and future wife Felicity (Rachael Stirling) aren’t so sure.

The real event that rocked Roald was a controversial 1983 book review he wrote of “God Cried,” a work harshly critical of Israel’s 1982 invasion of Lebanon.

In his write-up, Dahl called all Jews “a race of people” who’d “switched so rapidly from victims to barbarous murderers.”

He conflated the government of Israel with the global Jewish population and compared the Middle Eastern country to Nazi Germany.

Dahl then deplorably doubled down in a follow-up interview with the New Statesman.

“There’s always a reason why ‘anti-anything’ crops up anywhere,” he said. “Even a stinker like Hitler didn’t just pick on them for no reason.”

Audience members new to this shocking information can’t help but think: This is the same guy who dreamt up Matilda Wormwood and the chocolate river?!

In a word: Yes.

Coming in hot, Rosenblatt imagines a contentious emergency visit from a representative of Dahl’s New York publisher, the made-up Jessie Stone (Aya Cash), to his under-construction English country house to address the backlash, which has led several US booksellers to threaten not to carry Dahl’s forthcoming “The Witches.”

She wants an apology, full stop. However, the 66-year-old author is unmovable.

Refereeing the bout is his UK publisher Tom Maschler (Elliot Levey), who considers himself more English than Jewish. He’s chummy with Roald and believes his writer’s contributions to kids’ reading are too important to jeopardize. Many probably would still agree.

Beyond the actor playing the creator of “The BFG,” it’s Levey who’s the MVP. Anybody who’s ever tried to bring down the temperature of a room while ignoring their own boiling fury within will vividly see themselves in Tom.

And Tom has a truly unenviable job as peacemaker here.

“Giant” uses the past to talk about Israel today, and the spats are expectedly heated and palpably uncomfortable. But newsiness wasn’t Rosenblatt’s intent. He finished his final draft two months before the Hamas attacks of October 7, 2023.

Whatever the date, the arguments are all but ripped from the headlines.

“Israel invaded Lebanon in self-defense,” Jessie maintains. “What would your government do if militants constitutionally committed to wiping Britain off the map started firing rockets into Kent from the French coast?”

Says Dahl of Israel’s founding: “They laid claim, they maneuvered and they took… Because you see what you need to see: a sanctuary — not another’s home.”

As the confrontational play rumbles on, Dahl’s commonplace talking points queasily devolve.

He becomes an object lesson in how anti-Israel rhetoric can casually slide into full-throated, unapologetic racism.

And, frankly, “Giant” depicts how easily the public will shrug at that. Dahl’s confidence about his legacy was proven correct, after all. The 1990 “Witches” film, “Matilda the Musical” on Broadway, Steven Spielberg’s “BFG” and Timothée Chalamet and Johnny Depp’s Willy Wonka movies all came along after his grotesque comments. 

Most people know nothing about any of this, which is why Rosenblatt’s play from London has been a hot topic.

His first act is tight, focused and exciting. When we return from intermission, though, the bickering continues and the story feels stuck in place. Characters change, I suppose. Felicity, Tom and New Zealand maid Hallie (Stella Everett) go from tolerating him to tolerating him less. A messy afternoon turns messier. Yet “Giant” comes to its inevitable conclusions half an hour or more before the bows.

The appeal, therefore, lies not so much in the end destination as watching an actor of this caliber inhabit a figure so complex and thorny.

How to make an often cruel man who casually spews repugnant remarks watchable? Call Lithgow!

First off, the towering 80-year-old Tony winner bears a striking resemblance to the man, right out the box. But it’s Lithgow’s ability to be quiet and sweet and seconds later booming and scary that makes us squirm in our seats over our own feelings toward the writer. At times, we really do like him.  

The actor’s well-rounded, seismic Roald will be on the defensive, weaponizing his over-6-foot frame, massive intellect and huge temper. All giant, indeed. And right away he’ll snap into a kindhearted old man — the nurturing papa who Dahl readers dream is behind the prose. A camouflage, perhaps.

It’s that softie who calmly asks the play’s most chilling question.

“Can you no longer read my books to dear Archie?,” he says to Jessie of her son. “If it’s in me, then it’s surely in the books too.”