Presidential secretaries are a devout sisterhood, fiercely faithful through midnight sandwich runs and foreign crises. When it comes to secrets, they're as safe as houses. Evelyn Lincoln worshipped Camelot. Rose Mary Woods may have erased Richard Nixon's 18 1/2 minutes. And Helene von Damm, although she moved from secretary to White House personnel director, edited "Sincerely, Ronald Reagan"--a book of letters compiled by a fervent apostle.

But Susan Clough is back from Plains, Ga. She's a dropout of one of the nation's most exclusive sororities.

"It was," she says, "a nightmare down there."

Even so, her return to Washington was abrupt. Former White House advisers and staff members say Jimmy Carter asked her to resign as his secretary and special assistant, a decision partly provoked by an evening in Washington's La Fonda restaurant. According to people who were there, Clough told a former staffer--at a crowded table--a story about personal matters involving the former president and his wife. A friend called Carter several days later. A day after that, Clough was out of a job.

"Oh, beans," says Clough. "I was not fired. When I left, it was best for both of us." She describes her departure from Georgia as a "mutual decision" over a "difference of opinion."

"Yes," she adds, "we had a conversation about what had been misinterpreted and conveyed to him. Someone thought I was going around saying something unpleasant." She says she told the staffer to have a colleague phone her so she could "apprise him" of the rumors she was concerned about.

Clough, who had a different Washington profile than other presidential secretaries because she was single, attractive and especially close to Carter, had slowly become miserable working in the former president's roots--a place where, as she describes it, you can't get Dannon yogurt and the name Rimsky-Korsakov draws a stare.

"Let's face it," says one former staff member. "If it's your home and you're an ex-president, it's one thing. If you're a single woman, it's another."

The beginning of the end was in January 1981, when Carter had a talk with Clough in the Oval Office. Clough says she'd assumed she'd work for him in Atlanta.

"But he said," says Clough, " 'Now Susan, I really have been worried about whether you would like Plains.' And I'm sitting there thinking, 'My God, he said Plains. He didn't say Atlanta, he said Plains.' And he's sitting there talking, 'But I really think you'll like it. It's a very nice place.' And I'm still thinking, 'He said Plains. Plains.' Then he finished, and I said, 'Mr. President, how many eligible bachelors are there in Plains that you think I would enjoy being with--or would enjoy being around me?' And he did not hesitate in his response. He said, 'Well, there's a military base nearby, isn't there?' "

Susan Clough pauses for effect here. "I didn't say anything," she says. "But I think I had on a blouse like I have on today, with an opened-up neck, because I could sense that my skin was breaking out. In a red rash."

She talks for several hours at the home of friends. She is 37, divorced and the mother of two children. She worked first for Jody Powell when Carter was governor of Georgia, and won out over Maxi Wells, Carter's campaign secretary, for the White House job.

She's been living in McLean since November, after nine months of opening up the Plains post office so the former president could have his Atlanta paper by 7:30 a.m.--and one month of living in the Best Western because she couldn't find housing. Her resignation letter, signed "With my love and best wishes to you, Rosalynn and Amy" is dated Oct. 31; Carter's two-page acceptance of it, handwritten on Nov. 4, praises her for "a brilliant mind and superb talents."

Her friends wondered why she'd even gone to Plains in the first place. But she says she felt her work wasn't finished--"just as grammatically, when you have a sentence structure, you have places for a comma and a period at the end." Her job was to help set up the office and handle the classified material the former president might need for his book. In reality, that meant delivering mail and figuring out what to do with a birdhouse she says was sent to Carter by a fan.

Her tale of nine months in Plains sounds like an episode from "The Perils of Pauline." She began by house-sitting for a Baptist deacon whose wife, she says, didn't like her cigarettes and the liquor she kept in the pantry. Soon after, a back injury sent her to the hospital--twice--with a ruptured disc. When she was released, the deacon's wife wanted the house back. She moved into the Best Western.

"So I'm in this motel room, flat on my back," she says. "The manager came in and hooked up the Home Box Office and Showtime, so at least I had something different to deal with. It was horrible."

By midsummer she'd found an apartment, but work relations in the small staff office had grown increasingly tense. There was some unhappiness expressed about the quality of her work. Clough, who is described by former associates as "high-strung" under a calm surface, didn't help the situation.

And she wasn't seeing Jimmy Carter.

"That was difficult," she says. He worked in his study at home, a short bike ride from the Plains staff office. He usually was eating breakfast with Rosalynn and Amy when she dropped off his newspaper at 7:30. At other times during the day, when she dropped more mail and staff work in his in-box, he'd often be gone.

"He'd gone from an area where everyone wanted and needed to be around him and needed to show they had a relationship with the president, so he needed to be able to get away and have some sense of privacy. Which is fine. But . . . you want to see the people you work for."

And then there was the matter of her social life. In nine months, she had two dates. The first was with a college professor who, she says, talked about Space Invaders. The second was with a group of people from Plains; they drove to a restaurant 35 miles away. She wasn't invited to the Carters' because, she says, "the staff doesn't go over. They didn't in the White House, they didn't in the governor's mansion, they don't in Plains. The Carters have a great feeling toward the people who work for them, but I can see where it is equally easy, perhaps, for the people who work for them to feel that they're not very much more than hired help."

Now she's job-hunting, either in corporations or public relations. She's not exactly sure what she wants to do. She's "thinking" of writing a book.

She still keeps up with Carter. "I've sent him a note from time to time," she says. "He's sent me a note from time to time." She's asked if she thinks he's happy in Plains.

"It would not be fair for me to answer," she says. "It's a question for him. He would say he's happy."

As for herself: "It's nice to be back feeling like a person again. I spent four years saying hello to all three shifts of presidential protective detail. I was at work before they came on duty at the 7 o'clock shift, and I was there at 3 o'clock, and for those that came back at 11 o'clock . . . you don't realize how far away you got from things when you were there. Human relations. Family relations. You find like you've almost been like a Rip van Winkle for four years. The fact that they have soap operas on in the evening is amazing. And when people start talking about 'Mork & Mindy,' you're not sure if they're talking about an animate or inanimate object."

But the parting with Carter was "difficult. The closer you are, the harder it is . . . but it was evident both to me and the Carters that this was not what I wanted to do with the rest of my life."