- Note: Silent Hill is set around October - November 2004.
On a dark night in Ohio, Rose Da Silva and her husband Chris chase their adopted daughter Sharon, who has been experiencing severe nightmares and sleepwalking, after she wanders from their house and almost walks off the edge of a cliff. Their only clue to the girl's condition is her repetition of the name "Silent Hill" during her episodes. Desperate for answers, Rose decides to take Sharon to the abandoned town of Silent Hill in West Virginia, despite Christopher's opposition to the plan.
On the drive to Silent Hill, Rose stops at Smitty’s to ask for directions. Cybil Bennett, a police officer from Brahams, watches the mother and daughter with a hint of suspicion, mostly after a scene of Sharon becoming distraught at somebody "changing" her drawings into disturbing, borderline occult imagery, which was actually done by Sharon during one of her fugues. Cybil soon asks if Rose needs help, but Rose declines and heads on her way. Dubious that these are two "ordinary" people, Cybil takes note of Rose's license plate. Rose proceeds on her drive to Silent Hill and Cybil attempts to pull her over. After noticing the turnoff to Silent Hill, Rose drives off quickly to escape her. Suddenly, the figure of a young girl wanders out in front of the car and Rose is knocked unconscious in the following crash.
Rose awakens to find that Sharon is missing and that she is on the outskirts of the town of Silent Hill, shrouded by the Fog World and steadily-falling ashes. Rose searches the empty streets of the town for her missing child. After following what she thinks is her daughter's figure into a dark alley, Rose experiences a surreal shift into a darker version of the town. She discovers a mutilated figure clothed in mining gear hung to a wire fence, complete with bloody floors and fences made of metal grating. Suddenly, Rose is attacked by a Grey Child. Dozens more show up, causing her to flee into a nearby building. Rose stumbles and is about to be overwhelmed by the creatures when the Grey Children and the surface of the room around her begin to disintegrate, and she loses consciousness. Upon awakening, she finds herself back in the Fog World inside of a dilapidated bowling alley.
Venturing out once more, Rose finds one of the main roads leading out of Silent Hill gone, collapsed into an abyss of fog. A mysterious woman in ragged clothing, Dahlia Gillespie, arrives and speaks of the terrible things done to her own daughter, Alessa, by the townspeople. Dahlia claims that Sharon is actually her own daughter and not Rose's. After Dahlia almost pushes Rose off the edge of the collapsed road in an almost insane rage, Rose runs back to her car and finds a drawing of a school in Sharon's sketchbook.
Suddenly, Cybil appears and places Rose under arrest for attempting to flee from her previously. As Rose is placed in handcuffs, Cybil reveals she too crashed and woke up in Silent Hill. They attempt to head back to the Brahams police station but discover that the road out of the town has mysteriously disappeared, resulting in Cybil beginning to believe Rose's claims that something is seriously wrong with the town. Backtracking the way they came to find a radio tower, Cybil sees something wandering towards them through the fog. As it gets closer, they realize it is another one of the town's Armless Men and it starts to shoot boiling acid at Cybil. While Cybil shoots at the monster, Rose takes the opportunity to run back into the town. After slipping the handcuffs to the front of her so her hands have limited use, she uses bus signs to find Midwich Elementary School, where she believes Sharon is.
Inside the school, Rose sees the figure of a child who looks like Sharon run into the girl's bathroom. She enters the bathroom and opens one of the bathroom stall doors to discover the body of a janitor (Colin) wrapped in barbed wire with a piece of a hotel keychain in his mouth. Rose takes the keychain and is about to leave when strange suited figures arrive. They spot her and Rose uses the keys she finds in the main office to keep them out of the bathroom. The figures leave quickly as a warning siren blares. Rose switches on her flashlight and sees the bathroom physically begin to rot and degrade as it shifts into the Otherworld. The body of the janitor is now alive and crawls along the floor still wrapped in barbed wire. Rose manages to escape before he catches her.
Meanwhile, Christopher has studied reports and online articles about Silent Hill, and the dangers it possesses. Worried for his wife's safety, he takes it upon himself to drive out and rescue her. He is reluctantly aided by Officer Thomas Gucci after Chris begs the officer to help him find his missing wife. Under the guise of keeping Christopher safe from the harms of the underground coal fire and other natural dangers of the town, Gucci guides the worried husband through the town. The officer reveals his father once owned the local barber shop, and talks about how everyone fled the town due to the coal fire. He sympathizes with Christopher, but is more immediately concerned with the man's safety and is keen to leave.
Eventually they reach the school, where Rose currently is still trapped in the Otherworld. Although the two of them cannot see each other, at one point they walk through the same area at the same time, and Christopher believes he feels Rose's presence, even smelling her perfume. However, Gucci doesn't believe him, shrugging off the sight of a school door opening and closing by itself. Chris and Gucci ultimately leave the town without much hope of finding her.
Rose runs through the dark and rusted hallways and collapses in tears, believing she can't go on. As she is about to be overrun with Creepers, Cybil suddenly shows up and saves her, having been dragged into the Otherworld along with Rose. Trapped inside a storeroom, the two of them are attacked by Red Pyramid, resulting in a hectic fight for their lives. While dodging the Great Knife, Cybil fires at the monster's arm as he yanks at a metal bar barricading the door. Just as the monster is about to break into the room, he ceases his attack and the school shifts back into the Fog World.
Meanwhile, Christopher has ignored Gucci's orders for him to go home, and has broken into the Toluca County Archives in a desperate search for any information that could help him in his search. He discovers documents showing the town was abandoned after a terrible fire 30 years prior, along with a photo of Dahlia's daughter, who bears a remarkable resemblance to Sharon. Christopher is apprehended by Officer Gucci when he tries to question Sharon's Toluca County Orphanage, and is told to stop investigating Silent Hill or risk being arrested. In exasperation, he finally relents and heads home.
Back in Silent Hill, Rose and Cybil arrive at the Grand Hotel, where they encounter a young woman named Anna. Searching the building, they visit Room 111 and discover a secret passage to a sacrificial chamber, where Rose encounters a little girl who resembles Sharon, albeit much darker: Dark Alessa. After Dark Alessa bursts into flames, another siren blares out and warns of another impending shift to the Otherworld. Anna implores Rose and Cybil to follow her to the local church, where she believes they will be safe.
On the way there, the Otherworld begins to consume the church grounds. Anna doesn't survive as Red Pyramid grabs her and rips her skin off. Rose and Cybil find refuge in the church, which is spared from being transformed by the Otherworld where they discover the remaining townspeople; a religious cult (the Brethren), headed by a woman named Christabella. Christabella tells them that a "demon" controls the town and that Rose must face the "darkness of hell" if she wants to find her daughter. After convincing Christabella that she wants to find the "demon" for answers, Rose is taken to Brookhaven with Cybil to find it.
There, Christabella discovers the likeness between Sharon and Alessa from Rose's locket and condemns Rose and Cybil as witches. Cybil is captured as she defends Rose, who escapes the clutches of the cult and descends in an elevator into the basement of the Otherworld hospital. After a close encounter with monstrous Dark Nurses, Rose finds a badly burned adult Alessa lying in a hospital bed, unable to walk or speak. Meanwhile, a nurse (Lisa Garland) in red hospital robes is crying and covering her face. Dark Alessa appears and explains why Alessa is like this. Rose learns that Dark Alessa is the manifestation of the dark side of Alessa's soul.
In a flashback, Rose discovers that Silent Hill had a history of ritual witch burnings. Alessa herself was condemned as a witch for not having a father and an attempt to burn her 30 years ago went disastrously awry, resulting in a devastating fire destroying the town. In her hatred, Alessa began manifesting psionic powers and ended up creating Dark Alessa and the Otherworld. Since then, she has been shifting reality to the hellish nightmare world in order to hunt down the cult members who hurt her all those years ago. Rose is told that Sharon is the manifestation of Alessa's remaining innocence and goodness, and was taken to the orphanage by Dark Alessa, where she was later adopted by Rose and Christopher. Dark Alessa warns Rose that Christabella will know where Sharon is hiding (Nathan’s Drugs), and that she's already making plans to burn her, just as she did to Alessa.
After realizing what she needs to do, Rose agrees to help Alessa gain her final revenge to save her daughter. After explaining that the church's protection from the Otherworld prevents her from getting inside, Dark Alessa then makes Rose absorb her so that she can enter the church. After this, the camera pans over to the nurse sitting in the back of the ward, still crying. She uncovers her face to reveal that she has been crying blood, a result of Alessa's psychic attack on her 30 years earlier.
Rose enters the church soon after Cybil has been burned to death by the townspeople and sees Sharon is about to suffer a similar fate. She confronts the townspeople and Christabella with her new knowledge of the truth, attempting to convince the cult that they are in denial of their own fate. Christabella stabs Rose in anger, claiming that Rose has been corrupted and is an agent of the "demon". Rose's wounds cause her blood to drip onto the church floor, releasing Alessa's tainted essence and opening a portal into the Otherworld. Dark Alessa and Alessa's adult form rise out of the portal, and proceed to kill Christabella and the townspeople with long tangles of barbed wire, leaving Dahlia, Rose, and Sharon as the only survivors. Sharon and Dark Alessa lock eyes, causing Sharon to faint.
Rose and Alessa leave Silent Hill and return home. At the same time, Christopher returns home from his search of the archives. Although Rose and Alessa are in the same room as Christopher, the same situation as the one at the school is present. Neither one can see the other, but Christopher still appears to feel Rose's presence and the door has mysteriously opened by itself. As Sharon leaves the room, her expression turns dark, indicating that Alessa's two halves have finally rejoined after 30 years, and that Sharon is now the complete Alessa.