In the impactful opening sequence, a powerful proton blast erupts from a mine shaft at the Shandor Mining Company, shooting into a swirling storm beneath a midnight sky. An old pickup truck, driven by a bearded elderly man, emerges from the mine shaft and speeds down a lonely rural road. This man, whose identity is gradually revealed, clutches a ghost trap containing a spirit. As he drives, an unseen horror gives chase, ultimately causing the truck to crash into a cornfield. The driver, Egon Spengler [Oliver Cooper] stumbles from the vehicle and rushes to a dilapidated farmhouse. He prepares a foot pedal switch to bait the invisible spirit, but his plan backfires when the electric towers short out. Scurrying indoors, he stashes the ghost trap under the floor and readies his PKE meter, only to be suddenly attacked by a spectral presence, leaving behind an ominous spirit orb.
The narrative shifts to Callie [Carrie Coon] and her children, Trevor [Finn Wolfhard] and Phoebe [Mckenna Grace], who are being evicted from their apartment. Callie receives notification of her father's death at his farmhouse in Oklahoma, prompting a family journey to gather possessions from the decaying house filled with clutter. They soon meet Janine [Annie Potts], the Ghostbusters’ receptionist, who reveals that Egon was heavily in debt and that the farm holds little value. During a severe earthquake-like tremor, Phoebe discovers the PKE meter hidden under a chair, igniting curiosity about her grandfather's true legacy.
In a small southern town where they are staying, Callie, Trevor, and Phoebe try to adapt. Trevor is particularly taken with a girl named Lucky [Celeste O'Connor], who works at the local burger joint. Meanwhile, Phoebe begins to explore the farmhouse, guided by the mysterious PKE meter. After being introduced to her summer school teacher, Gary [Paul Rudd], who is more focused on his own research than teaching, Phoebe impresses him with her knowledge of Seismology. As the days progress, strange occurrences lead Phoebe to a chessboard where she unwittingly engages in a game with a ghost.
Discoveries unfold as Trevor finds Ecto-1, their grandfather’s iconic vehicle, and Phoebe uncovers Egon’s hidden lab. They come to understand that Egon was a Ghostbuster, recognizing the gravity of their findings. With the help of Egon’s spirit, Phoebe repairs a proton blaster and goes on a mission with Podcast, her new friend, capturing the ghostly entity known as Muncher. Amid the chaos, they are apprehended by the sheriff's office but use the opportunity to contact Ray Stantz [Dan Aykroyd], who sheds light on their grandfather’s past and the team's tragic split.
As the plot further unfolds, Callie's strained relationship with her father reveals her sense of abandonment, while the kids find in Egon’s lab that his "dirt farm" was actually a clever ruse to conceal numerous ghost traps to ensnare Gozer. As they delve deeper into the mystery, they realize the mine operates as a portal for evil spirits, the source of the town's seismic tremors.
The tension escalates with Gary’s eerie encounter at Walmart, where chaos ensues, culminating in a demon dog attack. Back at the farmhouse, Callie discovers her father's memory board, leading to a dire confrontation when she is possessed by a spirit. With determination and courage, the children retrieve Ecto-1 and work to trap the malevolent forces threatening their town.
As the climax approaches, the kids brace themselves for a final showdown against Gozer and the revived demon dogs. With guidance from Egon’s spirit, Phoebe's bravery shines through as she helps her family confront their fears, culminating in a powerful moment of reconciliation. Just when all seems lost, the original Ghostbusters—Ray, Peter Venkman [Bill Murray], and Winston Zeddemore [Ernie Hudson]—arrive to confront Gozer, joining their efforts with the new generation to protect the world from the ghosts of the past.
With a poignant farewell, Egon’s spirit reconciles with his family before vanishing into the night sky. The surviving Ghostbusters forge a new connection with the Spenglers, ensuring the legacy of the Ghostbusters lives on as they head back to New York City in Ecto-1, where their adventures began. The film ends with callbacks to the past intertwined with hope for the future, setting the stage for a new era of ghost hunting amidst the nostalgic tones of the classic theme song.
A mid-credit scene teases the reunion of Dana Barrett Venkman [Sigourney Weaver] and Peter, while a post-credits moment hints at Winston’s new role as a protector of the Ghostbusters' legacy.
