“Marcel on the Train” is not a comedy, although the play’s star and cowriter Ethan Slater promises that there’s laughter to be had.

“We kind of knew that it was a show that effectively made people laugh until the stakes got too high to laugh anymore,” says Slater of the new production, which was extended the day before its first preview on Feb 5. The play opens Feb. 22, and is set to run through March 22.

The actor, coming off two years of “Wicked” film promo for his role as Boq, is sitting in the cafe outside the intimate Lynn F. Angelson Theater in New York in mid-January. He just finished a rehearsal of the piece, which he cowrote with director Marshall Pailet. “Marcel on the Train” lands at the East Village theater after its initial 2024 workshop during the Williamstown Theatre Festival, a prominent summertime incubator for new creative work in the Berkshires. Even in its early unstaged format, “people responded really strongly to it, which was exciting,” says Slater, reflecting on the experience.

Slater stars in the intimate show as famous French mime Marcel Marceau, born in 1923. Marceau, whose onstage alter-ego was Bip the Clown, made numerous appearances on TV and film screens until his death in 2007. While there’s plenty to mine from Marceau’s multi-decade performing career, Slater and Pailet chose to focus on a period before the stardom, when Marceau was a young man helping Jewish children escape the Nazi regime during WWII.

“The thing that first piqued our interest was this one little story, this anecdote of his life. That the world’s most famous mime, before he even really went to drama school, was part of the French Resistance smuggling orphans out of France,” says Slater. “It is a story of saving children, and the right that children have to grow up without the fear of being hunted. And it’s also the story of this young man, who is an artist, trying to do his best in the world, and how he becomes the person he will grow into. All of it is really packed into one train ride.”

The play focuses on one high-stakes train ride to the Alps. Accompanying a group of Jewish children disguised as boy scouts, Marceau leans on mime-ing and physical humor to ease the group’s anxiety as they evade detection. “In reality, he did three or more and saved upwards of a hundred children’s lives,” adds Slater. “But we wanted to really concentrate that story, and make it one night of theater.”

Slater has been heavily influenced by silent film comedians and clowns throughout his career —  he based his movement as SpongeBob, his breakout role, on silent film comedians like Laurel and Hardy, and finds inspiration from Buster Keaton and Charlie Chaplin — but was surprised to discover that there was a famous Jewish mime who wasn’t on his radar.

“ For anybody who went to a Jewish day school, it feels like you know anyone who is Jewish — I know every baseball player who was Jewish, I know every actor who was Jewish, and I didn’t know this story,” says Slater.

Originally born Marcel Mangel, he changed his name to Marceau to avoid being IDed as Jewish during the train rides. “ It really is the story of how Marcel became Marcel,” adds Slater, who gets to flex his own mime skills throughout the play. “ Marcel was trying to keep these kids entertained and keep them happy in the face of the scary world outside of the train. And I think our goal with the play is to do that same thing, to keep the audience happy and enjoying the fun.”

Slater met Pailet, his creative collaborator, when he was 18 and performing at a Fringe festival in D.C., in a racy experimental play that the actor now describes as “a humiliation ritual.” But the early humiliation paid off: after seeing Pailet’s own production at the festival, Slater asked him to grab a coffee to talk shop about “ what it means to be an actor and be a writer.”

A few years later, while Slater was starring in the “SpongeBob SquarePants” musical on Broadway — a role that would earn the actor his first Tony nomination — he auditioned for a workshop of a play directed by Pailet. The pair went on to work together on several plays, and then during COVID the pair began writing together. They’ve since cowritten four or five plays. “ It’s just been a really unbelievably fruitful collaboration,” says Slater.

For the pair, “Marcel on the Train” is deeply personal, rooted in shared lived experiences.

“ Marshall and I started [‘Marcel on the Train’] right after the birth of his oldest son. And now we’re both parents, and it’s a really big part of our worldview,” says Slater, who carries a photo of his son on the back of his phone. “When we started it, we were just coming out of COVID, and a lot of the issues that are present today were present then, but as murmurs in the collective consciousness,” he continues. “Now, they’re blaring sirens in the collective consciousness. And we’re looking at this play, and it feels ever-of-the-moment.”

Beyond its contemporary resonance and ties to the current sociopolitical moment, Slater hopes that “Marcel on the Train” will entertain — and move — audiences.

“ It’s a hopeful story. It’s a story of the power of silence in art. It’s the power of art for living,” says Slater. “And it’s really a story of humanity.”