The action is happening in 1994 Los Angeles and revolves around the lives of Jerry Fabin and Charles Freck. Jerry is plagued by a strange belief that his house, body, and dog are infested with aphids that cannot be gotten rid of. He attributes the spread of these aphids to "Carrier-people," individuals who unknowingly bring them into his home. Charles visits Jerry, and together they pretend to collect large aphids in jars for further examination.
Charles, also known as Freck, contacts his drug dealer in search of a substance called "slow death" or Substance D. Unfortunately, the dealer informs him that he is currently out of stock, causing Freck to worry about a severe shortage of the drug. While driving, Freck notices a police cruiser behind him and quickly fabricates a cover story to avoid suspicion of being high. However, the police officers pay no attention to him.
Freck decides to go to a walled and guarded mall at night to try and obtain some Substance D. While sitting in his car and observing pedestrian traffic, he spots a familiar face, Donna, who is a dealer he has encountered before. He follows her, but when he approaches and calls her by name, she denies knowing him and even brandishes a small knife. Moments later, she stops and looks back, suddenly recognizing Freck. They walk back to his car, and he asks her for some Substance D, but she informs him that there is a shortage. However, she promises to get more in a day or two, which feels like a long wait for Freck. Despite the delay, the prospect of having a two-week supply of 120 tabs brings him relief.
Jerry Fabin, on the other hand, is now confined in a "Federal Clinic" due to brain damage resulting from excessive Substance D use. Meanwhile, Freck begins to notice signs of withdrawal, experiencing shakiness, indicating that he is becoming dependent on the drug.
Bob Arctor, an undercover narcotics agent, who gives a speech to the Orange County Lion's Club. Arctor assures the audience that he is diligently working to eliminate the brain-damaging drugs being sold on the streets, specifically targeting the substances affecting their children. Privately, Arctor holds contempt for the "straights" or the law-abiding citizens who live in gated communities and view people with addictions as predators to be dealt with. During hisspeech, he deviates from the prepared script, prompting his supervisor, who is monitoring remotely, to urge him to stick to the planned content. Arctor briefly explains the effects of Substance D and makes a plea for empathy towards those struggling with addiction before abruptly ending his speech.
Later, Arctor wanders through the artificial landscape of Anaheim, California, which he describes as "plastic." He considers contacting Donna, the small-time dealer, as part of his ongoing effort to uncover the major sources of Substance D. These minor dealers like Donna are typically not arrested, as the authorities believe that the drug originates from a single lab and is distributed through a complex network of local dealers. The failure to locate the central facility raises suspicions that federal law enforcement may be involved. Arctor calls Donna and requests 1,000 tabs of Substance D, arranging a drop-off. Afterward, he visits a rehab clinic called "New-Path."
Freck and his friend Jim Barris, who is also Arctor's roommate, discuss the possibility of Freck checking into a New-Path clinic to overcome his drug addiction. However, Freck feels uneasy about the clinic's cold turkey approach to withdrawal. They discuss the physical effects of withdrawal, and Barris boasts about his ability to produce a gram of high-quality cocaine using inexpensive ingredients. To prove his point, they purchase a can of sunscreen and go to Arctor's house. Barris begins a process he calls "extraction," and Freck contemplates the idea of bartering cocaine with Donna in exchange for sex. Meanwhile, Barris examines Arctor's damaged cephalochromoscope and plans to write a book detailing how to legally manufacture drugs in one's kitchen.
Arctor, assuming the role of an addict seeking treatment, investigates a New-Path center in search of Doug Weeks, a notorious drug runner. However, the staff refuses to disclose whether Weeks is a patient at the facility. Frustrated, Arctor leaves the clinic, hoping for a different assignment or lead.
In this chapter, Bob Arctor(codenamed Fred) and his supervisor, Hank, go through a list of suspects while wearing scramble suits, which conceal their true identities. Arctor expresses his distress over his emotional numbness when faced with the devastating effects of Substance D. Unbeknownst to Hank, Arctor is actually reporting on the whereabouts and activities of his own undercover identity. Arctor, who works as a low-wage employee, uses and has become dependent on Substance D. Hank assigns Arctor, unaware that heis the same person, to keep tabs on Arctor himself.
At night, in Arctor's backyard, his roommate Barris tests a homemade silencer while haggling with Freck over stolen electronics. Arctor reflects on his past life, where he was once married with children but grew to despise the conventional "straight" lifestyle. He got divorced and went undercover as part of the drug counterculture. Arctor lies in bed and obsesses over his broken "cephscope" and Jerry Fabin's aphid delusion. Barris enters Arctor's room and theorizes that he may have damaged the cephscope, although it remains only a theory. Arctor takes two tabs of Substance D and falls asleep.
Arctor, Barris, and their roommate Ernie Luckman embark on a trip to San Diego. Arctor, under his special agent identity as Fred, informs his supervisor about their absence so that the agency can install "holo-scanners" in the house. Upon reaching their destination, Arctor drops off Barris and Luckman and visits Kimberly, a woman addicted to drugs who lives with her abusive boyfriend, who is also her dealer. When her boyfriend returns and she refuses to open the door, he slashes her tires. Since Kimberly does not have a phone, they call the police from a neighbor's apartment. Arctor suggests that she find another place to
stay, but she tells him to leave. On the drive back to Orange County, Arctor finds the situation absurd and can only laugh. However, while on the freeway, his gas pedal sticks, causing the car to accelerate uncontrollably. They narrowly avoid an accident, shut down the engine, and come to a stop. Upon inspecting the engine, they suspect that the damage was intentional. Arctor detects a smell of dog feces on the engine but questions whether he is hallucinating. He becomes convinced that Barris sabotaged both his car and his cephscope, and he fears that Barris knows his true identity.
The near-fatal accident serves as a reminder to Arctor of the constant danger involved in his profession. He realizes that anyone, including Barris, could attempt to kill him at any moment. Barris reveals that he has set up a recording system in the house to capture any break-ins while they are away. Arctor becomes increasingly paranoid and understands that instilling self-doubt in his enemy is more effective than a direct assault. He reflects on the hypocrisy and judgment that "straights" hold toward drug users, highlighting their own guiltin committing similar sins. Upon returning home, Arctor wonders if the surveillance crew has installed the holo-scanners. The house appears untouched until Luckman discovers a joint still smoldering in the ashtray, indicating that someone has been there. They suspect that drugs have been planted. They discuss possible courses of action, including selling the house and reporting the break-in to narcotics authorities. Suddenly, Donna emerges from the bedroom and confesses that she smoked the joint. Arctor is shaken by how he fell into the same paranoid mindset as the others.
Arctor, assuming the identity of Fred, meets with Hank, who informs him that six holo-scanners have been installed in his house. The video feeds can be viewed at a surveillance hub nearby. However, Arctor realizes a problem: if he, as Fred, manipulates the scanners to upload the data, his supervisors may question how the suspect, Bob Arctor, knows the scanners' locations. He is advised to creatively edit himself
out of the videos to avoid confusion. Hank reveals that they are gathering sufficient evidence to incriminate Arctor. They discuss using Arctor's house as another surveillance hub after his arrest. The meeting ends, and Fred is instructed to report to another meeting.
Fred is then greeted by two Orange County deputies who subject him to several tests to determine if he shows signs of Substance D addiction. A positive result would result in his assignment to a rehab clinic. The agents recall an incident where Arctor, Barris, Luckman, and Donna all failed to understand the "gear ratios" of a 10-speed bike, which is a simple cognitive task and a possible indication of brain impairment. Fred grows impatient with the testing, as his mind is consumed with thoughts of Donna and how to get closer to her.
Barris and Arctor attempt to repair Arctor's car, but tensions arise between Barris and Luckman, causing Freck to leave due to the tense atmosphere. While driving, Freck contemplates the deaths of musical artists from the recent generation and wonders if their demises foreshadow a darker era.
Back in Arctor's living room, Luckman shares a story about Donna stealing 18,000 stamps from a faulty postal machine and profiting from their resale. This anecdote makes Arctor question if Donna possesses a deceptive and unconventional side. When Arctor asks Barris to borrow his car to obtain drugs, Barris refuses, claiming that Arctor wouldn't be able to handlehis heavily modified vehicle. However, as a law enforcement officer, Arctor's own car is equipped with certain modifications, such as a device that alerts him if another police vehicle is nearby, a police scanner that appears as radio static to the untrained ear, and a hidden transmitter that broadcasts all conversations within the car to the authorities. While these modifications are relatively advanced, Arctor acknowledges that many car enthusiasts could similarly modify their vehicles, giving them an advantage over the police. Unable to use Barris's car, Arctor decides to walk to Donna's house, making a stop at the surveillance hub.
Arctor, assuming his Fred identity, watches the video feed from the holo-scanners. He observes Barris constructing a hash pipe while Luckman has dinner. Suddenly, Luckman starts choking on his food,
desperately trying to get Barris's attention, but Barris remains focused on his pipe. Luckman collapses, and Barris either fails to notice or deliberately ignores the situation. Eventually, Barris discovers Luckman on the floor, appearing shocked(although Arctor suspects it may be feigned), and calls for paramedics. To their surprise, Luckman regains consciousness and coughs up the food.
Donna drives by and picks up Arctor, informing him that she has obtained the 1,000 tabs of Substance D as requested. She invites him to a drive-in movie marathon featuring all 11 "Planet of the Apes" films. They drive to her apartment, and Arctor pays her for the drugs. Donna recounts several instances of her past thefts, but Arctor knows he will never report her. The thought of her enduring withdrawal alone and in prison is unbearable to him. Donna lights up a hash pipe, and they smoke together, providing a moment of intimacy for Arctor, albeit limited.
Fred(Arctor) observes himself on the holo-scanner entering the house and reciting long passages in German. He questions whether Arctor is losing his mind or pretending due to knowing he is being monitored. Luckman, who is sleeping in his room, is awakened by Arctor's recitation but doesn't recognize his voice at first. Startled, he grabs an axe, but once he realizes it's Arctor, he relaxes. The two men smoke a joint together and reminisce about their lost youth.
Fred is scheduled for a full range of percept tests by the Sheriff Department's psychological evaluator. He becomes frustrated with the inane chatter of Arctor and Luckman but listens as they discuss undercover narcotics agents and their private lives and motivations.Arctor wonders how anyone could do such a job, and Fred interprets this as a slip-up on Arctor's part. Fred eventually grows weary of the conversation and turns off the playback monitor. He compares his life and the lives of other undercover agents to the users they surveil, describing both as monotonous but with undercover agents being "imposters." Fred goes into the bathroom and consumes 10 tabs of Substance D before returning to watch the scanners.
The next day, Fred undergoes several hours of testing to evaluate his perception and dexterity. Afterward, he goes upstairs to meet with Hank
while waiting for the results. To his surprise, Barris is also present in Hank's office. Barris claims to have incriminating evidence against Arctor and admits to tapping Arctor's phone. He accuses Arctor of being an enemy of the state, conspiring to introduce Substance D into the United States, and being deranged and dangerous due to heavy Substance D use. Fred and Hank request specific evidence before taking any action.
The tests reveal a "competition phenomenon" between the two hemispheres of Fred's brain, indicating that neither hemisphere is dominant, likely a result of excessive Substance D use. Recovery depends on quitting the drug entirely, and Fred swears to quit immediately to avoid possible brain damage. The psychologists explain that Fred perceives the world as reversed, as if looking into a mirror. As they delve into the complexities of neurology and perception, Fred hears a voice proclaiming that seeing reality in reverse reveals its true nature and that not everyone will sleep in death. While the psychologists consider the implications of this "new cosmology," Fred confronts the unpleasant reality of withdrawal.
Fred sits in the cafeteria, fearing that he might be removed from the Arctor case before completing his mission. He becomes saddened at the thought of never seeing his friends again, especially Donna. He realizes that the holo-tapes are all he has left of his and Arctor's life and contemplates stealing the holo-scanner equipment to continue monitoring his friends' lives.
In Hank's office, Barris plays a recorded conversation that he claims features Arctor and Donna discussing a plot to steal weapons from Vandenberg Air Force Base and pollute the local water supply with a disorientation drug. As a formality, Barris is charged with providing false information to keep him in custody for his own "protection." Hank sends Barris's evidence to be evaluated for authenticity.He informs Fred that his psych report indicates severe impairment and suggests that instead of going to a rehab clinic, Fred should isolate himself in a remote cabin until the withdrawal subsides, advising him to bring his gun in case the pain becomes unbearable. While Fred contemplates where to spend his detox time, Hank reveals that he knows Fred is actually Arctor, leaving Fred stunned.
Fred decides to detox at Donna's place, and Hank arranges for Donna to meet him there. While waiting for a car, Hank informs Fred that the primary target of their surveillance is Barris, who is involved in something serious and dangerous related to guns. Fred realizes that he was being used by the agency to get to Barris. Donna drives Fred to a New-Path clinic as he experiences severe withdrawal symptoms. Along the way, they encounter a police officer who requests identification. Donna reveals herself as an undercover agent, and Fred is left at the clinic. Donna reflects on the cursed and unjust world that has caused so much havoc before shooting at Coke bottles in a delivery truck and crashing her car into the back of it. She walks away from the scene.
Arctor is informed that he will be transferred to a New-Path farm facility. Mike hopes that working with plants and tilling the soil can bring some healing to Arctor. Mike ponders if New-Path's purpose is to create conditions that force people into their facilities. The Executive Director of New-Path reveals that their mission has nothing to do with drug rehabilitation, leading Mike to suspect that their funding may come from the production and sale of Substance D. He also contemplates the idea that the "dead," like Arctor, may find some satisfaction in serving the living.
Arctor has a faint memory of living with two other men and a pet rat named Fred, which they claim they had to eat when they had no food. He listens in on a conversation in the lounge where patients discuss a hypothetical world with a single phone number connecting everyone, one doctor treating all ailments with aspirin, and a single law with the death penalty as the sole punishment. Eventually, society burns out. Arctor finds a humorous perspective on the story and gradually becomes recognized by the other patients for his ability to find humor amidst tragedy.
Arctor is transferred to a farmin Napa Valley, California. The manager of the facility gives him a tour of the closed operation where they cultivate hybrid crops. Arctor appears to struggle with maintaining a coherent conversation and can only repeat what the manager says. As they continue the tour, Arctor notices small blue flowers growing among the corn stalks. He inquires about the flowers, and the Executive Director responds that he is witnessing the flower of the future. However, he forbids Arctor from touching them. Arctor understands that these blue flowers are the organic form of Substance D. When the Executive Director and farm manager are not looking, he secretly places one of the flowers in his shoe as a gift for his friends.