PLOT
At a house party in Adelaide, Cole searches for his brother Duckett. When he finds Duckett and attempts to bring him home, Duckett stabs Cole and kills himself.
Sometime later, 17-year-old Mia is struggling with the second anniversary of her mother Rhea's death by an accidental sleeping pill overdose and her distant relationship with her father, Max. Mia, her best friend Jade, and Jade's little brother Riley sneak out to a gathering hosted by Hayley and Joss, where the main attraction is a severed and embalmed hand. Holding the hand and saying "Talk to me" enables someone to communicate with a deceased person's spirit, while saying "I let you in" allows the spirit to possess them. To prevent spirits from binding themselves to that person, someone else must end the possession before 90 seconds by pulling away the embalmed hand and blowing out a candle to cut the connection. Mia volunteers to go first and is possessed by a spirit that displays a menacing focus on Riley. Joss and Hayley struggle to break the connection, and the time limit is slightly exceeded.
Ecstatic over the experience, Mia joins Hayley, Joss, and Jade's boyfriend Daniel, at Jade's house the next night. Everyone except Riley and his friend James takes several turns being possessed, invoking different spirits each time. Jade refuses to let Riley participate, but all of the others indulge. When Jade leaves the room, Riley insists, and Mia lets him take a turn for 50 seconds. Riley appears to be possessed by the spirit of Rhea, who attempts to reconcile with Mia. Stunned, Mia stops the group from ending the possession in time to keep talking to her mother. The spirits overtake Riley's body, and they make him violently attempt suicide; he is hospitalized in critical condition.
Mia, now haunted by visions of Rhea, is blamed for Riley's injuries and shunned by Jade and her mother, Sue. Having secretly taken the embalmed hand, Mia offers Daniel to stay at her father's house for the night. Whilst platonically sharing a bed with Daniel, she witnesses a spirit appear and suck on Daniel's feet. When he wakes up, he instead sees Mia sucking his feet in a trance and leaves. Mia uses the hand to contact Rhea, who insists that her death was accidental and that she needs to help Riley, who is still possessed, and attempts suicide every time he returns to consciousness. Mia leaves the connection open and begins seeing her mother without the hand, losing her grasp on reality.
The friends track down Cole, who explains that a living body naturally expels invading spirits. Mia, fearing that Riley may not have time, attempts to contact him in the hospital by using the hand but is instead shown a vision of Riley being tortured by spirits in limbo. At home, Max reveals that Rhea's death was not an accident and reads her suicide note to Mia, apologizing for hiding the truth from her. Rhea's spirit tells Mia that Max is lying, and Mia hallucinates that she is being violently attacked by Max, causing her to stab the real Max inadvertently. Rhea tells Mia that Riley needs to die in order to be set free from his possession. Mia kidnaps Riley from the hospital, and Jade sees Mia pushing Riley in a wheelchair toward the highway. Rhea attempts to convince Mia to push Riley into oncoming traffic, but instead, Mia jumps into the oncoming traffic and dies.
Mia finds herself in the hospital, where she sees a fully recovered Riley talking to Jade and Sue while Max leaves in an elevator. Nobody responds to her; she has no reflection in the mirror, and her hands are disfigured. After becoming engulfed in darkness, she sees a hand extended over a candle in the distance. She grabs it and is suddenly summoned to a house party in Greece, where a partygoer holding her hand is urged to speak and tells Mia, "I let you in".