The Hills of Lethe, one of Chicago's largest cemeteries, has been sold to developers planning to erect condominiums on the site. On April 5th workers move the current inhabitants to a temporary rest in the Cook County Warehouse. One of the workers knocks a cheap casket against a drum, and a canister the size of a hat box rolls from the collapsed end of the box into the space between stacks of stored goods.
That night insomniac Mrs. Rita Baker is awakened by the sounds of a motorcycle, coming from her own garage. She turns on the lights and walks down the outside stairs. As she reaches the bottom step and turns to the garage door, a ghostly figure bursts through it; a motorcyclist roars into the chill Cicero night – a motorcyclist without a head. As it goes, Mrs. Baker sees that the garage door is still intact. All the police can agree on is that the twenty year old model BSA motorcycle had been stolen from her garage, and that it was amazing anyone had got it to run after so much time.
The next day, Joseph Morton returns his cab to the Domino Cab dispatch garage. Morton begins to cross the garage as the same motorcyclist roars around the bend, now carrying a sword. The rider closes on Morton, forcing him to dive between two vehicles. He runs away but the rider circles around and catches him, slashing him low on the back and knocking him into a pile of cushions. Morton struggles to get his feet beneath him as the rider circles around again and closes. Diving again, Morton evades one more pass, but on the rider's return, Morton can only shake his head in a mute "no." The dispatcher watches in horror as the rider cleaves Morton's head from his body.
Kolchak arrives after the police and begins snapping pictures. The silhouette chalked on the oily cement clearly lacks a head. Kolchak notices Captain Jonas noticing him, and begins to fiddle with his camera. As he heads to the exit, Jonas intercepts him demanding to know who let him in. Kolchak indignantly replies that the founding fathers – who guaranteed a free and unfettered press – allowed him in. Jonas is unimpressed. It seems that Jonas is now a captain – a promotion earned for breaking an important case. He intends to use his new rank to make changes, starting with a ban on pictures until he grants permission. He demands Kolchak's film – after irate objection, Kolchak opens the camera to reveal – nothing. He's forgotten to load the film. Jonas laughs; Kolchak is his own worst enemy! Then the dispatcher raises his voice and Kolchak hears "whole head gone." He asks Jonas if the victim was beheaded but Jonas' light mood has evaporated. Just then, Kolchak hears a truck behind him and turns to discover his car being towed. Sputtering at Jonas, he races out and manages to climb into his car before the truck can pick up speed.
Later, Carl visits Neil at the morgue to learn about Joe Morton's death. A contribution to Neil's "scholarship fund" buys Carl a look in the drawer, where he confirms Morton was beheaded. In Neil's expert opinion, he was beheaded by a sword. Joe Morton was wearing a bullet-proof vest when he died. Citing the high cost of education, Neil cadges another contribution before showing Carl the vest – split in the back.
Next on the itinerary is a visit to a motorcycle showroom. There Carl quizzes owner Herb Bresson about the tracks he filmed in the dispatch garage. Bresson tells Carl the tracks belong to a Johannson Road Monarch 560x18 tire. Bresson wants to sell Carl a motorcycle but Carl manages to maneuver him back around to the tires. Bresson says such tires would only be found on an antique bike – the Johannson tire company went down the tubes some time ago. This particular model of tire was made for the BSA bikes – the "beezers." Bresson admits the tracks are those of a tire in perfect condition that nevertheless must be twenty years old. He finishes by mentioning that the tires were popular with the bike games of the 1950's – the Bishops and the Jokers, both of which have since disbanded.
The night of the sixth, Henry Barlow "Studs" Spake is attempting an honest living as a telephone lineman. He calls in to report a completed repair and knocks off for the night. As he climbs down the pole, a motorcycle engine grows louder. At first Spake ignores it, but when it grows very loud he looks up and sees the headless apparition closing in. He evades it by jumping into a ditch – after two unsuccessful passes, Spake scrambles back up the telephone pole and out of the ghost's reach. It races away into the night.
Carl returns to the office in the morning; Tony surprises him with an appearance at the office. Tony's ulcer put him in the hospital and he has only just been discharged – with a chalky medicine to take and strict instructions to avoid stress. Accordingly, Carl hesitates to tell him about the story. Tony presses, Carl demurs, but finally relents, revealing that he's still working the cab driver murder. Tony starts to get upset. Calming him down, Carl explains how Morton's vest could not possibly have been shredded like it was, no matter how fast the bike was moving. Tony spins the idea into a story he likes – one that suggests the police released an incorrect cause of death. But Carl takes it just a little too far, telling Tony that kind of bike hasn't been seen in twenty years and that it would take superhuman strength to slash a bulletproof vest the way that Morton's was. Tony's shoulders slump a bit. Quietly, he collects his ulcer medicine and takes another dose. Carl goes on: taxi dispatcher Norman Cahill was present at Morton's murder and disappeared. Why have the police sequestered him? Emily pipes up; she has found Cahill through a friend who is a nurse. Cahill is in Mercy General, psychiatric ward, room 312.
Carl enters the Mercy General psychiatric ward claiming to be Carl van Damme, official police sketch artist (but no relation to van Gogh). The floor nurse demands credentials but Carl layers on the compliments and manages to slip past the bemused lady. In the ward room, Carl finds Cahill strapped in bed. Cahill tells Carl about the headless motorcycle rider. Carl asks if it could have been the light, or some other visual trick but Cahill is adamant and claims to be as sane as anyone. Cahill goes through the incident point by point – the headless rider was riding the same kind of bike Morton himself once rode. Carl wants to know if Morton was a member of a bike club, but the nurse has shaken off the flattery and ends the interview.
Over at police headquarters, Carl drops in on the beleaguered Captain Jonas. Jonas tells Carl he's releasing no information; Carl shoots back with a question: Has Jonas notified the board of directors? This begins Carl's deft manipulation of Jonas with a fiction that Morton was heir to the immense Morton Mining and Manufacturing fortune. In the course of proving Morton was not a mining heir Jonas reveals a wealth of information about Morton's real past as a punk, a criminal, and a member of the Jokers – a bike gang of the 1950s. By the end of the visit, Jonas actually insists Carl plant himself in a chair. Jonas then tells him about Morton, Studs Spake, and the Jokers. At the end of it, Jonas orders Kolchak out of the office and assures him he'll get no help – completely oblivious to the wealth of information he just provided.
Carl crashes the visitation for Joe Morton. On the way in he meets Studs Spake and a couple of guys from Spake's new gang, the Devil's Advocates. Representing himself as a documentary filmmaker, Carl requests an interview. Lila Morton hushes the group several times as Carl brings the conversation around to the death of Morton. Two of the Advocates, Electric Larry and Snow White, begin to mock Studs. He'd earlier dragged them to a cemetery to recover something he'd buried a long time ago. The mockery brings Studs' temper to a boil and Lila Morton ejects them from the viewing room; Carl manages to remain behind. He asks Lila who might both ride a twenty year old bike and want Joe Morton dead – she immediately denies knowing any such person. She claims she and her sister and Joe left that life behind long ago. When Carl asks if "things that won't stay buried" could refer to a killer without a head, Lila suggests Spake and his friends are on drugs and says she has no idea what they're talking about. When Carl points out how scared Studs looked, and how scared Lila looks, Lila asks him to leave her alone. She breaks down, remembering Joe's fondness for Buddy Holly – just until Carl leaves the parlor. As soon as Carl leaves the room, Lila recovers her composure.
That night Carl visits the only warehouse he knows of with connections to cemeteries – the Cook County Warehouse. The old door's hasp is already broken so he steps inside. Wending his way past piles of tarp covered boxes he spots Studs searching the warehouse. Flashlight in hand, Studs makes his way slowly through the narrow aisles, eventually knocking a box loose. The watchman tries to stop Studs but cannot; Studs scares him back to his tiny office where he dials for police help.
A motorcycle engine roars into hearing range, attracting Studs' attention immediately. The headless phantasm rounds a corner, sword ready, and begins to chase Studs. The gang leader evades it for a couple of passes, but just as the police arrive the ghastly specter races by Studs and shortens him by a head. Then it leaps the police car and roars off.
The next day sees Vincenzo jealously eyeing Ron and Emily as they eat lunch. Behind a cabinet Carl enjoys a pizza. And all Tony has is a bowl of bland ulcer-friendly mush. Vincenzo finally can't stand it – he secretly calls down and orders a lunch he'll enjoy. Then Carl returns to his desk with a very large book from the Chronicle file. Tony also notices a picture Carl took the previous night and calls it a classic Kolchak Special – the head chopped off. But Carl points out the gap between the figure's shoulders and the top of the photo and tells Tony the subject's head was chopped off twenty years ago. Carl's taking books from the Chronicle file to find articles about that long ago decapitation. Emily pipes up with something related: a guillotine exhibition at the Museum of Science and Industry.
Carl finds the article: On August 22nd 1956 the decapitated body of twenty year old Harold Baker of Cicero was found near Route 15. The article mentions that Harold Baker was also known as "Swordman" Baker and was a member of the Bishops, a local motorcycle club. And…Baker's head was not found near his body.
Carl races out of the office. The arrival of Tony's lunch cuts his protests short, allowing Carl to escape to the museum. There he finds Professor Eli Strigg and his assistant Louie getting the exhibit ready for its opening the next day. The guillotine jams and Strigg is unhappy. Carl offers Strigg the publication of a story on the exhibit, piquing the professor's interest. Strigg is dismayed to discover Carl's interest lies in the supernatural aspects. Pressed, he scornfully declares Carl's interest is in "wives' tales." Among these was the story that common graves and careless gravediggers during the Reight of Terror sometimes resulted in the separation of heads and bodies. According to legend, headless specters wandered the streets of Paris, attempting to exact revenge on their executioners. Parisians instituted a program to rebury the heads with the proper bodies and to ensure better care in the future; legend says this put an end to the problem.
That night, Lila Morton's sister Coral leaves her job at Lamino's Pizzaria. She never makes it home – the headless rider catches her in the middle of the street on his first attempt.
Carl stops at Lila Morton's house. He finds her hurriedly packing and tells her that however far she's going, it's not going to be far enough. She orders him out and he says he'll leave as soon as she tells him about Harold "Sword" [sic] Baker. Clearly she knows who Baker is. She tells Carl that Baker's death nineteen years ago was an accident. Carl is incredulous; he wonders how someone might be decapitated by accident. It seems Studs, Joe Morton, and Turk Pelletier put a wire across the road to knock Swordman off his bike, while Lila and Coral watched. But Studs set his end too high, and the wire struck Baker's head from his body. Nineteen years ago, the headless rider murdered Pelletier and the Jokers secretly buried him. Before his death, Pelletier had carried a canister containing Baker's head; Studs realized they had to reunite Baker's head with his body to put his spirit to rest. Studs buried the head with the body and for nineteen years – until the Hills of Lethe were excavated – Baker rested peacefully.
A motorcycle roars by and then there is a knock at the door. Lila is terrified; Carl snatches the door open but the visitor is no specter. It is Captain Jonas with his own theory – a costumed biker has decided to avenger Baker's death. Jonas knows the connection between the victims but doesn't accept the supernatural explanation. Carl claims the head must be reunited with the body – Jonas scoffs.
Carl realizes Jonas will never do what's necessary to put the ghost to rest so he returns to the Cook County Warehouse. He follows his flashlight beam past chalked names marking the locations of unearthed coffins. When he knocks over a pallet the new security guard doesn't even bother to investigate – he just calls his boss and tells him it's happening again and that he's getting out. Carl is alone in the barn of bones. Down a narrow aisle he discovers a tarp-covered pile of coffins. One bears the scrawled name "Baker". Pulling back the tarp, Carl finds the box in question – old, open at one end, and…empty save for some scraps that might once have been a shroud. The doors creak. A short walk away behind some chemical drums and a pallet Carl finds what has rolled there – a metal canister and inside it, a skull. But it was a mistake to pick up the skull – it draws the attention of Baker's ghost, who now counts Carl among his enemies.
Clutching the canister, Carl dives under the swinging sword and down a side aisle. The spook makes another run but Carl evades it again. On its third pass, Carl snatches the skull from the canister and throws it weakly. The missile knocks the headless ghost from its bike. Moments later, there is only a skeleton amidst the wreckage of a very old bike – a skeleton with its skull back where it belongs.