At a rowdy house party in Adelaide, a teenager named Cole searches desperately for his erratic brother Duckett. When he breaks into a locked bedroom, Duckett stabs him in the face before driving a knife into his own throat. Months later, 17-year-old Mia struggles with the two-year anniversary of her mother Rhea's death from an apparent sleeping pill overdose. Mia feels distant from her father Max and spends most of her time with her best friend Jade, Jade's little brother Riley, and their mother Sue. Videos surface online of wild parties where teenagers experience bizarre trances using a mysterious embalmed hand encased in ceramic, allegedly severed from a dead medium. Mia, Jade, and Jade's boyfriend Daniel attend a gathering hosted by Joss and Hayley. Mia volunteers to try the hand. Following the instructions, she lights a candle, takes the hand, and says "Talk to me." A decomposing ghost appears before her. When she says "I let you in," the spirit floods her body in an overwhelming, ecstatic high. The teens pull the hand away before the strict 90-second safety limit expires, blowing out the candle to sever the connection. The group gathers the next night at Jade's home. Riley begs for a turn. Reluctantly, they allow him a brief 50-second round. When Riley grasps the hand, a spirit claiming to be Mia's deceased mother Rhea possesses him, speaking tenderly to Mia. Mesmerized and desperate for closure, Mia blocks the others from ending the session. The timer blows past 90 seconds. The spirit violently turns, repeatedly smashing Riley's face against a wooden desk and gouging his eye before they manage to pull the hand away. Riley is rushed to the hospital in critical condition, trapped in a coma with continuous seizures. Mia becomes relentlessly haunted by gruesome phantoms. A spirit mimicking her mother visits her room, whispering that Riley's soul is being tormented in limbo and that the only way to save him is to end his suffering. Max tries to comfort Mia by showing her Rhea's genuine suicide note, but the spirit convinces Mia that Max is lying and attacks him. Driven mad by hallucinations, Mia steals Riley from the intensive care unit in a wheelchair and wheels him onto the median of a busy freeway. The spirit urges her to push Riley into oncoming traffic. At the final second, Jade races toward them. Mia either jumps or is pushed, tumbling into the highway traffic.

Mia awakens bruised and disoriented on the highway. She walks back to the hospital, where the surroundings are strangely quiet. She sees her father Max walking away without noticing her. Entering Riley's room, she finds Riley fully conscious and laughing with his mother and Jade. Mia looks down and notices she casts no shadow. The hospital lights begin extinguishing one by one, plunging her into pitch-black void. Suddenly, a small candle flame flickers to life on a table in front of her. Sitting across from her are unknown partygoers speaking a foreign language. A hand reaches across the table and grabs Mia's cold hand. A teenage boy looks at her and says, "Talk to me." Mia realizes the horrible truth: she died on the freeway, and she is now the trapped ghost being summoned through the hand from the other side.