When DEL PIERCE was five years old he was possessed by a demon, and the demon never left. Somehow Del trapped it, locked it away, and managed to grow up almost normally. And now, twenty years later, the demon is breaking out.

Del is far from the only victim of possession, though “possession” and “demon” are just words for things no one understands. In this world, men and women throughout the centuries have been seized by alternate personalities, independent intelligences that jump from person to person. The 1940’s, however, launched an epidemic of possessions in America that continues to this day. The dozens of new demons echo heroes and villains from pulp fiction, golden-age comics, and folklore, and their actions have warped history. THE TRUTH, a Shadow-like figure with twin .45 automatics, executed O.J. Simpson. THE CAPTAIN has repeatedly possessed soldiers in combat, making them into real-life Captain Americas. THE KAMIKAZE killed President Eisenhower, bringing Nixon to power years early, and triggering a “War on Possession” that meant decades of persecution for Japanese-Americans.

Del’s demon, THE HELLION, is a Dennis-the-Menace-like wild child who plays pranks and can shoot the glasses off your face with his slingshot—a “prank” that cost Del’s mother her eye.

Del doesn’t remember how he came to regain control of his body from the Hellion, but it’s been sleeping in his head ever since he was a boy. When the demon seemed to awaken when he was a teenager, a therapist helped him quiet the thing. But a car accident awakens the demon again when Del is 26, and this time nothing he tries—therapy, drugs, a stay in a psych ward—can put the demon back into its box. At night the demon takes control while he’s sleeping, wrecking furniture and running amok. He starts chaining himself to the bed at night like Lon Chaney waiting for the werewolf.

Del embarks on a tour of competing explanations and remedies for possession that reads like a tour of genres, from science fiction to noir murder mystery to Lovecraftian horror, with side trips into philosophy and Jungian psychology. Del first pins his hopes on DR. RAM, a neurologist attending the International Conference on Possession who claims to have located the neurological basis for possession. Dr. Ram refuses to help Del, and the doctor is promptly killed by the demon called The Truth, or someone dressed as the Truth. (Telling the fake demons from the genuine is no easy task. Case in point is PHILLIP K. DICK, a writer Del meets at the conference who claims to be possessed by an artificial intelligence named VALIS. Dick’s friends think he may be faking, but “Valis” tells Del that sometimes he pretends to be Dick pretending to be Valis—a fake fake.)

Del then becomes convinced that O’CONNELL, another attendee at the conference, can drive out the Hellion. Mother Mariette O’Connell, an Irish woman with a shaved head, is a priest from a Catholic splinter group who became famous for a string of exorcisms before she dropped out of sight. After the conference, Del and his brother LEW track down the priest at a lakeside town in upstate New York. The lake is home to TOBY, a gentle, Sumo-sized giant of a man, who for years has portrayed THE SHUG, the area’s only tourist attraction.

O’Connell, however, also refuses to help Del. There’s no way to kill a demon or force it out of a host, she says, short of killing the host. The best you can do is entice a demon to possess someone more attractive, a moral impossibility for Del, because the Hellion would surely take the body of some innocent five-year-old. Del is the only person O’Connell’s ever heard of who has trapped a demon, and perhaps if others learned this trick humanity would have a tool to use against the demons. Del doesn’t have that kind of time, however; the Hellion is growing stronger and soon Del will lose control.

Before Del can decide his next step, he’s captured by a squad of paramilitary nut-jobs called THE HUMAN LEAGUE. The league believes that A.E. Van Vogt’s novel Slan, about powerful telepaths who secretly rule the world, is the truth masked as fiction. The league was led to Del by BERTRAM, a friend Del made in the psych ward. To Bertram’s shock, however, the league plans not to enlist Del in their cause, but kill him, reasoning that if Del dies with the Hellion inside him, one less demon will be in the world. Before they can execute Del, the Shug attacks (the monster is a true demon after all) and picks off the league one by one. In the struggle, a hand-cuffed Del is tossed into the lake. As he’s about to drown, Del instinctively jumps from his body and possesses that of his brother, Lew. Lew pulls Del’s body from the lake before it dies. O’Connell realizes what’s happened, and she commands Del to re-enter his body.

Del is confused by what’s happened, but O’Connell suspects the truth. She takes Del to see THE WALDHEIMS, Jungian psychologists who offer yet another explanation for the demons: they’re archetypes from the collective unconscious, dressed up in the trappings of American culture. Under hypnosis, Del let’s the Hellion “out”—and what emerges is not a demon, but a scared child. Del quickly takes back control of his body, but now he knows the truth: Del is the demon who never left. All these years, the boy he possessed has been trying to escape.

After a period of shock and confusion, Del decides that he cannot stay in this body. But where can he go? O’Connell and the Waldheims convince him that because he’s a demon, he must know more than he thinks about the true nature of demons. Using the Waldheims’ extensive files, Del discovers that some of his own memories match images created by THE PAINTER, a silent, art-creating demon. One recurring image of a farm is the same as one Del drew in RADAR Man #1, one of the comics that he and Lew created as boys.

Del and O’Connell retrieve the comic from Del’s mother’s house, and clues in the comic lead them to a small town in Kansas. Down the hill from an old hospital, Del and O’Connell find the farm from the drawings. The silo and barn are wrecked, but the house is strangely preserved, and in an upstairs bedroom they find a boy’s bedroom filled with stacks of comics, pulp novels, and dime magazines. Del is irrationally certain that the boy who lived here is the source of the demons. Del is determined to stay in the house that night, and O’Connell reluctantly agrees.

In the middle of the night Del is awaked by THE PIPER, a lascivious, trickster demon. O’Connell has slipped away to the hospital, and the Piper hints that she’s trying to kill all the demons. She has motivation: As a child she was repeatedly possessed by a demon called THE LITTLE ANGEL, a curly-haired girl who showed up at the bedsides of the old and terminally ill to end their lives with a kiss. More recently, Del realizes, it was O’Connell who was possessed by the Truth and used by the demon to kill Dr. Ram.

Del follows The Piper across the fields to the hospital, and he realizes that all the Painter’s images were drawn from the perspective of someone in the top floor of that building, looking down on the farm. At the hospital, dozens of demons are acting out their roles: cowboys fighting with Vikings and pirates, the Shug battling the Captain, the Fat Boy raiding the cafeteria. It’s Pandemonium. Only Valis is unaccounted for.

Del makes his way to the top floor. In the room that overlooks the farm is BOBBY NOON, once a twelve-year-old with a too-active imagination who was almost killed in an accident, now an old man who’s been in a coma since 1944. He’s the source of the demons, a dreamer with the ability to bring his pulp fantasies to life. O’Connell lies on the floor outside the room, unconscious and bleeding, stopped by Bobby Noon’s guardian, THE BOY MARVEL, a caped figure who is the first demon Noon ever dreamed to life. Still fighting to enter the room is O’Connell’s childhood demon, The Little Angel. Del saves the Little Angel from being killed by The Boy Marvel, and as Del and The Boy Marvel struggle, the Little Angel manages to reach the old man and bestow her kiss.

Del expects to die with the Bobby Noon, but he lives. O’Connell and Del return to Del’s mother’s house. Del knows he can’t stay in this body, that the real Del deserves to live. Del faces his mother and his brother, and explains how the demon fell in love with them and decided to stay. That night, Valis—inhabiting the body of Del’s friend Bertram—enters Del’s room. When Valis didn’t appear at the hospital, Del began to suspect that there was more than one dreamer in the world, and Valis confirms it. There will always be dreamers, though maybe none as prolific as Bobby Noon. The demons, however, live on—characters don’t die with their authors.

The next morning, Del asks Lew to hold him down. Del knows the secret of jumping now. All you have to do is be willing to leave behind everything you love; you have to be willing to die. Del jumps.

Months later, THE BOY is having his sixth birthday. His life isn’t easy; he’s a six-year-old trapped in a grown man’s body, being raised by a fully grown brother and his suddenly older mother. The boy is visited that day by a strange man, and the boy recognizes him as the demon who used to possess him. The demon—temporarily inhabiting the body of Bertram—promises the boy that he won’t have to worry about being possessed again, and the demon is working with other people to shut down possession altogether. The boy is more impressed by the present the demon leaves: a copy of RADAR Man #1.