On a late afternoon last winter she and Christopher Plummer met me at the Loews Regency Hotel, in Manhattan, to talk about the 50th anniversary of the movie version of The Sound of Music, which is being re-released in theaters in April. For anyone who saw it originally, in 1965, it hardly seems possible that so much time has passed. Now that Plummer is 85 and Andrews is 79, you can imagine how they feel.

It was during the filming of The Sound of Music that Andrews and Plummer began a friendship, which, half a century later, is still going strong. Andrews’s husband, Blake Edwards, directed Plummer in The Return of the Pink Pantherin 1975, and they remained friendly until the director’s death, in 2010. (Edwards and Andrews had been married for 41 years; Plummer has been married to his wife, Elaine, since 1970.) In 2001, Andrews and Plummer co-starred in a live television production of On Golden Pond, and in 2002 they toured the U.S. and Canada together in a stage extravaganza called A Royal Christmas. By now, they have perfected the well-worn patter of an old married couple themselves.

Once Andrews’s kettle was pressed into service and the tea was brewed and poured, the two of them settled onto the couch in a suite to talk. They had just returned from a photo shoot. I asked how it went, and Andrews leapt in: “Well, I was dressed in black. He was dressed in black. We were against some white, I think. I had a great pair of earrings, and my hair was really exciting. It was done up rather wildly.”

“You didn’t notice me at all, did you?” Plummer asked wanly.

“No, I didn’t,” she answered vigorously.

He pouted. “I haven’t eaten anything for days,” he announced.

She responded on cue. “Oh, honeybun, that’s terrible!”

Heartened, he continued, “There was a charity dinner last night, and the food was so awful nobody ate anything.” She fumbled through her bags. He looked on hopefully, but she landed on a bottle of Advil. “I have to have these—I’m sorry,” she said, shaking out a few pills, which dropped onto the carpet. She picked them up and swallowed them anyway. “There were just so many stairs today,” she said, continuing to dig until she unearthed a Kashi peanut-butter granola bar. “I brought half a peanut-butter cookie with me,” she told him cajolingly.

He eyed it shrewdly. “Not half,” he said. “A quarter.”

O.K., guys. Part of the reason we’re here today is to talk about your 50-year friendship.

“What do you mean, friendship?” Andrews asked.

“Exactly,” Plummer said.

Through the decades, Plummer has remained unabashedly ornery about playing Captain von Trapp. He was, even in the early 1960s, a celebrated stage actor and chose to do the film primarily as training for playing Cyrano de Bergerac in a Broadway musical (a role that would not materialize until 1973). Instead, at 34, with gray highlights in his hair, he found himself shipwrecked aboard what he considered the Good Ship Lollipop as an unwitting party to seven chipper children, a warbling nun, and a bosun’s whistle. Indeed, whenThe Sound of Music was released, the reviews were awful. Pauline Kael trounced it as “mechanically engineered” to transform the audience into “emotional and aesthetic imbeciles when we hear ourselves humming the sickly, goody-goody songs.” In The New York Times, Bosley Crowther allowed that Andrews “goes at it happily and bravely” while noting that the other adult actors “are fairly horrendous, especially Christopher Plummer as Captain von Trapp.”

Whether Plummer likes it or not, the legacy of The Sound of Music feeds his currency. The incurably handsome, subtly grieving, widowered Captain von Trapp was always the heartthrob in the movie, never Rolf, the twerpy teenage messenger boy. The fact that it took a guitar-playing nun with bad clothes and good values to trump the elegant yet shallow Baroness is pure Hollywood justice. Off-screen, the well-born Plummer (his great-grandfather Sir John Abbott was prime minister of Canada) spent his life compensating as a notorious bad boy—drinking and carousing, skewering himself with self-deprecating humor as he happily trashed the conceited or self-important along the way. His 2008 memoir, In Spite of Myself, is a show-business tour de force.

Andrews is a different animal altogether. The Sound of Music followed Mary Poppins by six months; they were preceded by her Broadway triumph as Eliza Doolittle in My Fair Lady. Jack Warner famously rejected her for the movie version of My Fair Lady, hiring Audrey Hepburn instead (and dubbing her singing voice). During the 1965 Golden Globe awards, when Andrews won best actress in a musical or comedy for Mary Poppins, she made it a point to thank Warner in her acceptance speech.

She has been a movie star ever since. Although frozen in the minds of millions as an improbable hybrid of nanny and nun, Andrews is much more, obviously; her triumph both on-screen and onstage in her husband’s Victor/Victoria is an example of her range, along with her critically acclaimed dramatic turn in the film version of Duet for One. Besides her preternatural singing voice, what has always defined her is plain hard work. During rehearsals for My Fair Lady, her co-star, Rex Harrison, was disdainful of her dramatic abilities and wanted her replaced. The director, Moss Hart, dismissed the cast to spend 48 hours working solely with Andrews to improve her performance. As she tells it in her memoir, Home, when Hart finished, his wife, Kitty Carlisle Hart, asked how it went. “Oh, she’ll be fine,” Moss replied wearily. “She has that terrible British strength that makes you wonder how they ever lost India.”

-excerpts from Vanity Fair Hollywood