The reviews are mixed for foreign policy writer Tad Szulc's first novel, Diplomatic Immunity, but the cash register is ringing steadily. Moviemaker Frank Perry (his latest is "Mommie Dearest") agreed to pay $300,000 plus a percentage of the gross for dramatic rights to the book.

Meanwhile, isn't that Sally Shelton, former U.S. ambassador to Barbados and the eastern Caribbean, as Szulc's main character, the sexy, politically savvy "Julia Savage"? The fictional Savage is portrayed as the youngest female ambassador in the American diplomatic corps, just as Shelton was during Jimmy Carter's administration. And Shelton is Szulc's neighbor in upper northwest Washington. And Szulc did consult Shelton during the writing of the novel.

"I frankly am not certain what to say," says Shelton, who left her ambassadorship to consult with the World Bank and serve as a fellow at Harvard's Center for International Affairs. "I think anyone who would read the book would see some similarities but there are also some substantial differences. It's really a composite of (former U.S. ambassador to Nicaragua) Larry Pezzullo and (former U.S. ambassador to El Salvador) Bob White and me."

Although Szulc says she "was very helpful as a friend," he says Shelton isn't Julia Savage.

How does Shelton feel?

"I'm just enjoying Tad's success from the sidelines, and I'm thrilled for him," she says. "He's a brother, father and best friend all wrapped up in one."