Details of the novel's plot remain unknown, but a Kennett Square caterer thought a Chester County billionaire would pay handsomely to block its publication, authorities said.

The reason? The author allegedly promised thinly veiled and unflattering portraits of Mary Alice Malone, a Campbell Soup heiress, and her family.

Although federal authorities did not name Malone, details in the indictment against Agnes O'Brien, 54, offered clues to Malone's identity.

Calls Monday to Iron Spring Farm, Malone's renowned 1,000-acre horse-breeding operation in the Coatesville area, then generated a response from one of Malone's attorneys in New York City.

"Mary Alice Malone is the victim in the alleged extortion attempt by Agnes O'Brien; Ms. Malone cooperated fully with the federal authorities on this case," Daniel J. Horwitz said in a statement.

Malone, 60, whose worth was pegged at $2.2 billion in 2009 by Forbes magazine, making her 147th in its list of the 400 richest Americans, is a granddaughter of John T. Dorrance. He was a chemical engineer who discovered a new method for canning soup that begot the Campbell's empire.

O'Brien, who used to work for Malone and lived in a house she rented from her, is accused of trying to extort money from Malone by threatening to sell a novel and film rights. At one point, she is said to have demanded annual payments of $250,000.

Reached by phone Monday at her catering business, Aggie O'Brien & Co., O'Brien deferred comment to her attorney, Michael S. Zullo. He did not return multiple phone calls.

O'Brien was arraigned last week on three counts of extortion. She was released on her own recognizance, court records said, and will forfeit $10,000 if she fails to appear for her next court proceeding, which has not been scheduled.

Court records provide the following account:

O'Brien, described as a part-time household employee who averaged $20,000 a year from 1997 though 2009, as well as being a "friend" of Malone's, was discharged in January 2009 and vowed to "get even."

In July 2009, Malone decided to sell a house that O'Brien had been renting and notified her that her lease would be terminated. In December 2009, O'Brien, who did not want to move from the Chester County residence, sent an e-mail to Malone chronicling the book.

O'Brien described the writing as cathartic after she "got her feelings hurt." She touted the book as "fast and funny," and said she was not willing to be victimized "after 30 years of loyal service."

In a Jan. 8 phone call, a lawyer representing Malone offered O'Brien the opportunity to stay in the house for a monthly lifetime rent of $400 if O'Brien would hand over the manuscript to be destroyed.

O'Brien refused and made a counterproposal: an upfront payment of $200,000 and annual payments of $250,000 for the rest of her life. The attorney put the terms in writing Jan. 20 and sent them to O'Brien, who signed the letter and sent it back the next day.

Negotiations continued, and when O'Brien was advised that she was committing extortion, she contended that "she would write her book from jail if she were prosecuted."

O'Brien did lower her demand, however, to a "$200,000 interest-free loan, of which only $60,000 would be repaid"; annual lifetime payments of $150,000; and permission to occupy and "ultimately jointly" own the house she had leased.

Court records gave no details on how the alleged attempt unraveled.

The indictment said O'Brien "referenced specific instances of alleged conduct by the 'characters' that, regardless of the veracity of the allegations, would prove embarrassing" to Malone.

According to court records, O'Brien has had experience with financial strains. In 1995, she and her then-husband, Clarence Joseph O'Brien 2d, filed for Chapter 7 bankruptcy, two years after Chase Manhattan bank began foreclosure proceedings, citing the couple's failure to pay the $9,390-a-month mortgage on their 50-plus-acre property in West Grove.

During the foreclosure process, the bank, which eventually won a $1.3 million judgment against the O'Briens, contacted all previous mortgage-holders of the property whenever a sheriff's sale was scheduled, court records said.

On the notification list was Malone, who held a $50,000 one-year mortgage for the couple in 1993, court records said.