Margot Kidder is easily Harry Clark’s biggest fan.

She loves the stories Clark creates from snippets of musical life, sometimes buried deep in history. The language is so alive and, when combined with music, Clark and his Chamber Music Plus take her and the audience to another place.

She can’t quite find the word for what that place is, she said during a phone call from her Montana home last week.

“When you put beautiful words to beautiful music, you get this third thing and I don’t know what you call it,” she said, calling Clark a genius and gushing at the opportunity to work with him this weekend for the third time. “I think these pieces are exquisite.”

On Sunday, Kidder will take on the role of Ludwig van Beethoven’s sister-in-law Johanna in Clark’s “Sister-in-Law Beethoven.” It’s the story of Johanna’s bitter court battle with her brother-in-law over custody of her son.

Not many people know the story, which if told today would surely be fodder for tabloid TV. In 1815, Beethoven’s younger brother, Kaspar Karl, died and left custody of his 9-year-old son to both his brother and wife. But Beethoven didn’t want to share with Johanna; the pair were not fast friends, to put it mildly. So he took her to court and sued for full custody. It took more than five years of back-and-forths, most of them in Beethoven’s favor, before Beethoven finally won. The damage on young Karl was significant; at one point, he reportedly attempted suicide.

Clark picks up Johanna’s story at the point of Beethoven’s death in 1827, when half of Vienna turned out for his funeral. Kidder will perform the monologue as a dramatic reading and Clark, a cellist, and his pianist wife, Sanda Schuldmann, will perform works Beethoven wrote for solo piano and for piano and cello.

“I’m a big fan of Beethoven for certain moods. If you’re feeling grand or you have something to celebrate. Or if someone is dying,” she said with a laugh.

Kidder made her debut with Chamber Music Plus in Clark’s “A Rare Pattern” in 2010 and performed the work again in Phoenix. The veteran actress’s career includes her defining role in “Superman” and roles on TV. She will return to the small screen in a Canadian pilot she will film this spring, she said.

But she said she is particularly enamored by her performances with Chamber Music Plus. Being around classical music reminds her of her childhood growing up in mining communities.

“My mother was horrified that we were getting no culture,” she recalled. “So she would get the shortwave on the radio and turn on opera and sing along, which was mortifying if you had friends over.”

Her mother exposed her to books and classical music, which she said she resented when she was young. But as an adult and grandmother of two, the 64-year-old said she wishes she could thank her mother.

“Something deeply emotional happens with classical music that doesn’t happen with modern music,” she said.

If you go

• What: Chamber Music Plus “Sister-in-Law Beethoven.” featuring Margot Kidder, with cellist Harry Clark and pianist Sanda Schuldmann.

• When: 3 p.m. Sunday.

• Where: Berger Center for the Performing Arts, 1200 W. Speedway.

• Cost: $40 at the door or in advance at or 400-5439.