Plot
Jillian "Jill" Conway lives in Portland, Oregon with her sister, Molly, in Jill's house. One year earlier, Jill was kidnapped by a brutal serial killer who held her captive in a deep vertical hole containing the remains of his other victims somewhere in Portland's 5,100-acre Forest Park. Jill used one of the past victim's bones to stab her abductor when he arrived in the hole to kill her, and escaped using his rope ladder. When the Portland police were unable to find the hole despite an extensive search and discovered that Jill had been committed to a psychiatric institution after her parents' death, they believed the abduction only happened in Jill's head, and sent her back to a psychiatric facility.
Jill regularly goes to Forest Park with a map, searching for the hole from which she escaped. Meanwhile, she is taking self-defence training.
Jill works as a waitress in a local diner (Lucky Star) on the graveyard shift. Before Jill leaves for work, she observes Molly diligently studying for an exam, and when Jill phones Molly from work around 11 pm, Molly says she is about to go to bed, and asks Jill to wake her when Jill returns from work about 6:30 am so that she can resume studying. During Jill's work shift, she and her coworker, Sharon Ames, are generously tipped by a regular customer.
Returning home after work, Jill discovers Molly is missing. Knowing that Molly was unlikely to have suddenly changed her intention to sleep, or to have otherwise acted irresponsibly before an exam, Jill is convinced that the serial killer who took her has now taken Molly. Unable to reach her boyfriend, Billy, by phone, to confirm that Molly is not with him, Jill reports Molly missing at a familiar police station. Lt Bozeman, Sgt Powers, and Det Lonsdale dismiss her belief that her sister has been abducted as an unsubstantiated overreaction. They again believe Jill's story is "all in her head", a product of the psychological trauma she has been experiencing since the death of her parents before she first reported being abducted herself. Only the department's newest homicide detective, Det Hood, believes Jill. He gives her his card in case she needs any help. Jill is then told by Billy that he does not know her whereabouts.
Jill interrogates her neighbors and learns that a van with a locksmith company's name (All Hours) was briefly parked in front of her house overnight. She talks to the company's owner, Henry Massey, and his son, Nick. After Nick denies using the van overnight, Jill enters a company van in the parking lot, where she finds a hardware store receipt, dated the previous evening, for items that include those used during her abduction. She holds Nick at gunpoint and forces him to reveal that he allowed a stranger named "Digger" to rent the van for several hours overnight. Jill phones Sgt Powers to inform him of the incriminating receipt, but meanwhile someone from All Hours Locksmith has reported her gun-waving to the police. Sgt Powers insists that she immediately surrender her handgun, which, he reminds her, she cannot legally possess due to her time spent in a psychiatric institution. She disconnects the call, refusing to be sidetracked from her search for Molly.
Jill goes to the hardware store, where she learns Digger's vehicle description (burgundy Chrysler Imperial) and address (Royal Hotel). Meanwhile, police officers recognize her parked vehicle. About to leave the store, Jill sees the police searching her vehicle. She obtains permission to use the store washroom, but the prospect of escape through a window is blocked by a window lock. When police knock on the washroom door, she shoots the lock, enabling her to avoid capture.
Upon nearing the Royal Hotel on foot, Jill speaks with an adult male who confirms that the Chrysler Imperial owner lives at the Royal Hotel and that Digger's actual name is Jim LaPointe. She enters the unlocked door to LaPointe's vacated room and finds duct tape, pet food resembling that given to her by her kidnapper, and matches from the Lucky Star Diner. Jill encounters a janitor in the motel and pays him to rent his vehicle.
Jill returns a call from her psychiatrist, whom the police have contacted. The psychiatrist blithely asserts that Jill's belief that Molly has been abducted is an erroneous overreaction to Molly's unexpected absence and is due to Jill's trauma-based anxiety. The psychiatrist urges Jill to meet with her. Jill astutely suspects the police are waiting for her at the psychiatrist's office. Jill again refuses to abandon her search for Molly.
Jill visits Sharon and confirms her suspicion that LaPointe is the generous tipper from the diner. Sharon gives her his phone number. As nightfall settles, Jill's failure to stop at a stop sign prompts a police pursuit, which she eventually eludes. Having abandoned the rented vehicle, Jill revisits Sharon, who reluctantly lets Jill use her vehicle.
Jill calls LaPointe, who offers to meet her, and gives her the options of him going to her or her going to him. Jill chooses to go to him, and he gives her initial directions. While driving, she receives a call from Billy, who falsely claims that Molly has returned after going out drinking and sleeping overnight at a friend's residence. Jill again rightly discerns that this is another attempt by police to trick her into ending her search. She tells Billy she is on her way to meet with the abductor. Powers, upon learning that Jill's intends to meet with the alleged abductor at an unknown location, calls Jill to make another manipulative attempt to convince her to alter her plans, but that futile effort is interrupted by a call from LaPointe, who provides Jill with further directions to his location, a remote spot in Forest Park.
While she drives they continue conversing. LaPointe claims that he is not holding Molly. He describes in detail how a father and daughter formerly lived happily for many years together in a cave in Forest Park, a "magical place". He states he was surprised that the police search for the hole in which Jill said she was held was ended after only a week, given that the father and daughter lived in the 5000-acre park for many years without detection. He asks her to recount how she escaped from the hole. "You're a brave girl", he says, "driving out in the middle of the night to meet a man you hardly know". Jill eventually loses cellphone signal service. She must walk the final distance to LaPointe's campsite, where she finds and pockets pictures of LaPointe's prior victims.
Meanwhile, Molly breaks out of her restraints and emerges from under Jill's house. Molly tells Billy that she was hit by an assailant and dragged under the house. Powers and Lonsdale are shocked when they hear Molly's story, which confirms Jill's belief that her sister was abducted.
Jill finds the lantern-lit hole where LaPointe held her captive. LaPointe ambushes Jill and pulls her into the hole, intending to kill her with the same piece of bone that she stabbed him with before her initial escape. However, Jill shoots him and starts climbing up the rope ladder. When LaPointe grabs her and attempts to pull her back down, Jill desperately kicks LaPointe to break his hold and shoots him again. She then manages to climb out and extract the rope ladder, trapping LaPointe in the hole. After shooting LaPointe a third time in the leg when he does not tell her where Molly is, Jill demands that he tell her, promising to not shoot him again if he does. LaPointe tells her that Molly has been under Jill's house the whole time (evidently so that Jill would be lured into returning to the park to rescue Molly). Jill keeps her promise to not shoot him again, but instead pours a can of kerosene into the hole. As LaPointe begs for his life–"you said you wouldn't kill me"–Jill simply responds, "I lied". She then throws the lantern in the hole, burning LaPointe to death.
As Jill drives out of the park, she sees that Powers has texted: "Molly Safe. Come Home." Jill throws the handgun out of the vehicle window. Returning home, she finds Molly terrified but unharmed, with police officers and Billy present. As the sisters reunite, Molly expresses fear that LaPointe will return, but Jill assures her "we're fine, we're gonna be safe", then whispers further assurance (probably that LaPointe is dead) to Molly. When Powers asks about the man Jill went to meet, she says there was nobody there, sarcastically telling Powers, Lonsdale, and Hood, "It was all in my head."
Sometime later, Bozeman receives an anonymous package containing pictures LaPointe had taken of each of his victims bound and gagged, including Jill herself, and a map that indicates the spot in Forest Park where the police can find the hole. Realizing how wrong he was about Jill, Bozeman calls Powers into his office to investigate the new leads.
