Growing up in South Carolina, Millie Maree read romance magazines and dreamed. Her sister Gloria wasn't sure if it was at age 13 or 14, or whether she was reading True Story or Modern Romance, but she knows Millie found her life's ambition in ardent words on a pulpy page.

"She read a story about a woman who was an airline stewardess," Gloria Maree recalled at the trial of the man Zconvicted of murdering her sister. "And she had all these adventures and she met all these exciting people because she would travel. And she decided this was what she wanted to be."

In October James Edward Perry was sentenced to death three times over for slaying Mildred Maree Horn, her son and the boy's nurse. Today, opening arguments are scheduled in the trial of the man prosecutors say gave Perry his orders: Lawrence T. Horn, Mildred Horn's former husband.

They met on a plane. Millie had become a flight attendant. And Horn was an exciting person, a sound engineer for Motown Records, flying high between appointments with music business celebrities. His name was on recordings of the Temptations, the Supremes and even the "I Have a Dream" speech of the Rev. Martin Luther King Jr. He was tall, charming, quick to laugh.

They were married a year later in Las Vegas, but the 1973 wedding would be the high point on a roller coaster relationship. It long since had crashed to earth by the early morning hours of March 3, 1993, when Mildred Horn discovered the intruder in her Silver Spring house who shot her to death through one eye.

Her body was found in the foyer. Prosecutors said they believe that the 43-year-old flight attendant for American Airlines had come down the front stairs of her immaculate, two-story home after being awakened by a piercing alarm from her son's medical monitor. If so, 8-year-old Trevor Horn, the severely retarded, quadriplegic boy whose $1.7 million malpractice settlement was the reputed prize in an alleged murder-for-hire scheme, already was dying.

Beside his criblike bed lay the body of Janice Saunders, the overnight nurse who would not have heard the killer's approach over the sound of the boy's oxygen pump.

A Montgomery County jury decided that Perry, a hustler and self described storefront minister, shot both women and smothered Trevor, whose $25,000-a-month care allegedly prompted his father to order the murders.

Lawrence Horn's fate will be decided in Frederick, where his trial landed when the defendant exercised his right in a capital case to move proceedings from the original jurisdiction. Maryland law does not, however, let the defendant say where his trial will end up, and Montgomery County Circuit Court Judge Ann S. Harrington rejected his attorneys' complaints that because Frederick jurors can tune in to Washington television stations, they may have been exposed to too many of the wrenching details that emerged in Perry's trials.

"The two cases are very similar," said Montgomery Deputy State's Attorney Robert Dean, who also prosecuted Perry. Horn's attorneys declined to comment, citing an informal gag order.

The trial is predicted to last at least a month. More than 100 prosecution witnesses are scheduled to testify, many of them Detroit FBI agents who sat at wiretaps for weeks trying to catch Perry and Horn on the phone at the same time. They never did. But an ambitious examination of phone records exposed a web of 136 calls between each of their homes and pay phones near the home of the other.

As in the Perry trial, jurors will hear tapes of each man arranging the calls through a go-between, a Horn cousin who did prison time with Perry.

Harrington has not yet ruled whether they also will hear an answering machine tape, recovered from Lawrence Horn's Hollywood apartment, containing a cryptic conversation that prosecutors suggest may be an excited Perry reporting to his employer that he has just completed the murders. The tape was played for the jury in the Perry trial.

"I could take a picture of him . . . but I couldn't," says the voice identified as Perry's. "The noise -- you understand what I'm saying?"

The tape is the closest thing to direct evidence in what is an otherwise wholly circumstantial case. But that case includes more than 600 exhibits, and many of them document the alleged conspirators' attempts to escape detection.

Perry was undone partly by a bizarre how-to book called "Hit Man: A Manual for Independent Contractors." After police learned he had ordered a copy, they pointed out 22 points of overlap between its advice and the murder scene. The Maree family has filed an apparently unprecedented lawsuit against Paladin Press, of Boulder, Colo., which published the book, charging that it "aided and abetted" the murders.

In Horn's case, detectives said their prime suspect was undone in part by videotaped statements he made under oath as part of a lawsuit the Maree family filed to keep him from inheriting Trevor's estate.

The most evocative evidence emerged in the paperwork from $6,000 in money orders to Perry and his girlfriend that investigators traced from Los Angeles, where Horn lived. The return address was for the Sunset Boulevard building that now is home to Motown Records. The fictitious sender's name mystified detectives until they saw it on a death notice in the same edition of the Los Angeles Times that carried the obituary of Mary Wells, a Motown singer who died destitute.

"Lawrence loved, absolutely loved his work," said Horn's first wife, Juana Royster, an education administrator in Seattle.

They met when she was the receptionist at Motown, then housed in the Detroit building that would become known as "Hitsville USA." Horn was applying for work after coming home from the Navy. As a disc jockey on an aircraft carrier, he called himself "The Man with the Plan." Royster said she saw his talent for preparation the night in 1966 that she walked into her basement recreation room and found herself getting married, in a wedding her fiance had arranged secretly.

The marriage lasted only eight months, and although Horn ended it, the two remained friendly. Royster said she knew he had acquired a taste for the finer things and saw him go from driving an Oldsmobile to a Porsche. But she never detected any malevolence in him.

"He was absolutely fun," Royster said. "He was a wonderful person. He still is to me, because I don't have any other reference point."

At the Perry trial, Lawrence "L.T." Horn appeared only in a photograph. And in the cocked eyebrow of the color mug shot that prosecutors dramatically displayed before jurors, it was not hard to infer the gleam of something that Assistant State's Attorney Teresa Whalen called "diabolical."

But on the phone from the Montgomery County jail, Horn sounded like his old self to the first woman who married him.

"He was always upbeat," Royster said. "He would talk about all the reading he was doing.

"Invariably, he would make me laugh." CAPTION: Lawrence T. Horn is accused of hiring another man in 1993 to kill his 8-year-old son, Trevor; his ex-wife; and his son's nurse.