For much of his life, Matthew Roberts has suffered from night terrors. They're dreams, yes, but they're a lot more vivid than the usual REM-sleep brain tangents, and they often take him to the brink of what he describes as "an emotion beyond fear or horror." He might be sitting in bed with his amber eyes wide open, but a few feet away he'll see a cluster of aliens torturing human beings—melting their skin as if it were under a magnifying glass. "Sometimes I wake up covered in spiders," he says. "Just hellish stuff. Movie-nightmare stuff. Some of it I won't even tell you, I won't even describe."

As Roberts says this, he is wearing a black suit and sitting with a kind of magisterial stillness in a red leather banquette at a strip joint in Van Nuys, California. People often feel as though they've met Matthew Roberts before: His face is bracingly familiar in a way that makes you unsure of whether to stare or turn away. An aspiring singer, songwriter, and author, he works here at Rouge a few days a week as a DJ, pumping up the soundtrack for scantily clad dancers when they make a beeline for the pole or a waiting lap. It's a slow Sunday morning, though, so while everyone prepares for the first customer of the day, Roberts takes a moment to sip a soda and explain why he feels, at times, like Rosemary's baby.

He has come to this sensation by degrees. He was born in Chicago in March 1968 and adopted a few days later by a quiet, straitlaced couple from Rockford, Illinois. His childhood was placidly midwestern—well, except for those night terrors. He played football. He banged the skins in a garage band. He went to church and pledged his soul to the Lord. But after graduating from high school, he found himself drawn to rock and roll and the West. He moved to Los Angeles, enrolled in the Musicians Institute in Hollywood, met and became temporarily engaged to a woman named Gina, and gradually—at Gina's urging—got to wondering who his biological parents were.

Roberts pursued the mystery, but very slowly—the L.A. move came in 1986, but he didn't start digging into his genetic roots for a decade. First he found his biological mother. In 1999 he called an adoption-search organization in the Midwest, coughed up a few hundred dollars, and was given her name. She was living in a cabin in Wisconsin without a phone or a car, he says. "The adoption lady kind of warned me, 'Your mother's a little bit off.' Then I got a letter from my mother, and she was talking about her rhubarb and her cats, and I thought, well, she's just kind of a hippie. But at a certain point it became obvious that there was something wrong with her. Mentally." The woman, a Wisconsin native whom he calls Terry, said that his first and middle names at birth had been Lawrence Alexander. According to Roberts, she sent him food in the mail after warning him, in a weirdly winking way, that her own mother had suffered from Munchausen syndrome by proxy, a mental disorder that can lead parents to poison their children. "One time she sent me a jar of, like, mystery juice," Roberts says. "It had things floating in it. Then she asked me, 'Did you drink the juice?' And I said, 'No.' And she said, 'You're smart!' "

Roberts was beginning to get a sense of where those night terrors might have come from. Only gradually, he says, did his mother let the narrative wrinkles slip out: that he had been conceived during a hippie orgy in San Francisco in 1967, that his mother's participation in the orgy may not have been consensual, that there were four men present, that everyone at the orgy was dropping LSD, that his mother had apparently continued to ingest LSD in the months that followed. It was all eerily similar to Rosemary's Baby: Midway through Roman Polanski's 1968 film about the prenatal care and feeding of Satan's spawn, Ruth Gordon coaxes a pregnant Mia Farrow into gulping down a frothy, fetid glass of herbal goop. In the movie, Roberts says, "they were doing it to create an Antichrist. Well, in this case it just happened." That was a safe assumption, of course, until the day in 1999 that Matthew Roberts finally sent his biological mother a photo of himself, at about 30 years old, with his piercing eyes and his tangled nest of black hair, and she told him she realized which of the four men at the orgy had to be his father: Inmate No. B-33920 at the California State Prison in Corcoran, otherwise known as Charles Manson, the most demonic figure in the annals of American murder.