Sam, a 33-year-old man drifting through life in Silver Lake, Los Angeles, is captivated by conspiracy theories and the hidden meanings within popular culture. Unfortunately, he seems indifferent about his mounting rent issues while facing a shocking warning to "Beware the Dog Killer," a figure that has been mysteriously murdering pets in the neighborhood.
Everything changes when he encounters his new neighbor, Sarah, whose intriguing presence draws him in despite their awkward first meeting. After catching him peering at her, she surprisingly invites him over. Their evening takes an unexpected turn as they indulge in some cannabis and watch How to Marry a Millionaire. However, just as a romantic moment begins to unfold, the interruption from her roommates prompts Sarah to suggest he leave, with plans to reunite the next day.
The following morning, Sam wakes up to find that Sarah and her roommates have vanished without a trace. This sudden disappearance consumes him, compelling him to uncover the mystery behind it. As he investigates, he notices a peculiar symbol painted on the wall of Sarah's former apartment. This leads him through a bizarre series of high-profile Hollywood parties where he bumps into the band Jesus and the Brides of Dracula and a performance artist entangled in an underground prostitution ring involving struggling actresses. Yet, all these occurrences fail to provide Sam with any clarity or direction as he desperately tries to connect the dots.
Things take a darker turn for Sam when he sees a news segment about billionaire Jefferson Sevence, whose charred body was discovered alongside three women. Upon closer inspection, he recognizes a hat belonging to Sarah and a small dog, reminiscent of Sarah’s pet, that was also found dead at the scene.
In his search for answers, Sam reaches out to the author of Under the Silver Lake, an underground comic dedicated to peculiar neighborhood narratives. The author cryptically explains that Sarah's disappearance, the menacing dog killer, a mysterious figure known as the Owl's Kiss—a woman in an owl mask who allegedly seduces and kills her victims in their sleep—and the hidden messages sprinkled throughout pop culture are all tangled together in a larger conspiracy. The author also reveals his peculiar habit of surveilling his premises via security cameras.
However, tragedy strikes when authorities discover the author's lifeless body, deemed a suicide. Intrigued, Sam sneaks into the home and studies the security tapes, horrifyingly witnessing that the author’s demise was at the hands of the Owl's Kiss.
As Sam follows riddles encoded in the tunes of Jesus and the Brides of Dracula, he encounters the enigmatic "Homeless King," who guides him to a hidden bunker beneath Griffith Park that leads to an unassuming supermarket. Alongside the performance artist and her crew, he eventually crosses paths with "the Songwriter," an immensely rich elderly gentleman who claims to have penned a majority of pop music history. In a shocking twist, when the Songwriter turns hostile, Sam retaliates and fatally bludgeons him, employing a guitar once owned by his idol, Kurt Cobain.
Later at a lavish party in the Hollywood Hills, Sam encounters Millicent, Jefferson Sevence's daughter, and is astounded to also stumble upon his ex-girlfriend and her new partner. Millicent persuades him to take a dip in the Silver Lake Reservoir, where she gifts him a bracelet identical to Sarah's, once belonging to her father. This light-hearted moment quickly spirals into tragedy as Millicent is struck down by unseen assailants, sinking beneath the water, posing eerily like a scene from one of Sam’s cherished issues of Playboy.
In a gripping climax, Sam manages to flee and combines the bracelet, a cereal box prize from the author, and a map from Legend of Zelda to pinpoint a mysterious location absent from online maps. At this new site, Sam confronts a man and three women, brandishing a firearm. As the man reveals the shocking truth—that throughout history, affluent men have constructed underground bunkers to preserve their legacies as they transcend beyond life, accompanied by three wives—Sam realizes the grim fate that Sarah and her roommates have met was merely a ruse. Their supposed deaths were staged, and they remain alive in a sealed-off bunker, reachable through video calls.
In a heart-wrenching exchange, Sam connects with Sarah once again, who expresses that she willingly entered the bunker, finding peace in her assured fate. They share a poignant farewell, leaving Sam to ponder his own life choices. Just as Sam begins to lose consciousness, the Homeless King appears, incensed after finding dog treats in his possession. However, after Sam confides the truth behind the biscuits—merely a reminder of a painful breakup and memories of a dog he can never see again—the Homeless King releases him.
Returning to his apartment, Sam spends a surreal night alongside a neighbor whose parrot chatters an incoherent loop of phrases. From his balcony, he witnesses his landlord and a police officer come to evict him. To his shock, they discover one of his walls has been painted with the same strange symbol from earlier—a message urging him to "stay quiet," thrusting him deeper into the mystery that has taken over his life.
