Henry Fonda and his daughter Jane, who have wanted to do a movie together as much as their fans have wanted it, have found the perfect vehicle.

With Katharine Hepburn signed for the mother's role, the Fondas will co-star as father and daughter in the beautiful play "On Golden Pond," which has had critics rhapsodizing.

Filming is scheduled for next summer, and Fonda couldn't keep it a secret at the Kennedy Center on Sunday night and whispered it to close friends when he was being honored for lifetime achievement in the performing arts.

The play, written by 29-year-old American University graduate Ernest Thompson, opened at the Eisenhower Theater last January. It could have been written for the Fondas. He plays a cantankerous 80-year-old retired professor who for the 48th time is spending the summer at his Maine cottage with his wife.

Their 42-year-old daughter, Chelsea, arrives with her latest boyfriend and his 13-year-old son.

The plot is about aging and parenting and love.

One critic compared its "affirmation of life" to that of Thornton Wilder's "Our Town."

The instant New York attorney Arthur Christy's name was announced as the special prosecutor in the Hamilton Jordan cocaine-sniffing allegations, a lightbulb went on in the head of a youthful Manhattan book packager-publisher.

A phone call was placed immediately to Christy's son, Duncan, a professional writer living in San Francisco.

If the Jordan affair should drag on, instead of being quickly disproved and dismissed, the first offer has been made for the book rights.

The offer came from 27-year-old Armand Eisen, one of two Ivy League wunderkinds who founded Ariel Books in New York right out of school. Duncan Christy, who went to Harvard with the other partner, Tom Durwood, is currently finishing a book called "Wizards," which Ariel sold to Simon and Schuster.

Christy, reached in California yesterday, said that he had not yet discussed the offer with his father for "ethical reasons" and doesn't intend to do so as long as the investigation is under way.

"It is a very delicate situation," he said. "My father is the most ethical, scrupulous man in the world, and that's one thing he instilled in me. At this point, it's just an idea in Armand's head."

Christy is both the son and grandson of lawyers. His grandfather, Francis T. Christy, spent five years doing the legal work necessary to create and build Rockefeller Center.

When Art Buchwald walked into Sans Souci yesterday, who should be sitting there on the banquette he made famous but Rose Mary Woods?

Former President Richard Nixon's secretary was lunching with a longtime friend, public relations executive Robert Keith Gray.

Buchwald doesn't care. He has forsaken Sans Souci unless he gets invited there by someone else. He went yesterday to meet the American Film Institute's George Stevens Jr.