Rachel Keller and her 10-year old son, Aidan, moved to a quiet town of Astoria. Rachel gets a new job for the newspapers, and works for a guy named Max. Rachel investigates a mysterious death of a teenage girl involving Samara Morgan. Not long after, Aidan has a nightmare that Samara pulls him into the TV. He yells to call Rachel. Rachel and Aidan attend a county fair. Aidan feels nauseous so he wanders away into a public restroom.
The toilets flush dirty water up at him, which makes Aidan uncomfortable. He then stands in front of a mirror, and takes pictures of himself. In each picture, Samara gets closer to him. This is when he gets possessed by Samara Morgan. Rachel finds Aidan so they can go home. On the drive home, Rachel and Aidan are attacked by multiple deer in the car, who dodge and break the windows. Back at home, Aidan develops hypothermia, and his temperature was at 93 degrees, which was the same thing that happened to Samara.
Rachel brings him to Max's house, and attempts to give Aidan a hot bath, but he develops a fear of water. Rachel leaves Aidan in the bath while she leaves the room, but comes back only to find that the water has fled in the hallways and through the door. Rachel yells Aidan's name, but he doesn't respond. She busts the door open, and the water is not in the tub, but it has fled on to the ceiling. Samara has her hands on Aidan's back, and Rachel tries to call Aidan's name, but he looks up at her with demonic eyes.
The water falls back down and Aidan is at the bottom of the tub. Rachel reaches in, only to wrestle Samara back down. Rachel reaches again, and pulls Aidan out, who was waterlogged and coughing. Max walks in and suggests she take him to a hospital.
Aidan is hooked up to a monitor, and psychologist Dr Emma Temple sees marks on Aidan's back, and suspects Rachel of child abuse, since she reportedly suffered from Postpartum Depression. When really, the marks were caused by Samara. She asks Rachel to leave. Rachel visits Samara Morgan's biological mother Evelyn Borden, who has been in a mental institution for drowning Samara, and she also suffers from Postpartum Depression.
Meanwhile, at the hospital, Aidan wakes up and is looking very pale, and his temperature has gone down to 90.3. He telepathically makes Dr Temple commit suicide by injecting herself with a syringe. Aidan leaves the hospital, and walks back to Max's house. Max arrives home to find Aidan watching TV alone. Max attempts to take a picture of Aidan to reveal Samara, but Aidan refuses. Somehow, Aidan kills Max, which was not shown. Rachel comes back and sees Max's dead body in the truck. Rachel terrifyingly enters the house, where Aidan runs up and hugs her.
Rachel tells Aidan to go to sleep, but he responds "I never sleep". Then, she makes peanut butter jelly sandwiches, and puts sleeping pills in Aidan's sandwich. It makes Aidan go to sleep. Now Evelyn believed the only way to get rid of the evil in Samara was to drown her, and this was what killed her. Rachel brings a sleeping Aidan over to the filled bathtub to drown him. Just as she's about to do it, Aidan wakes up. He tells her it's him and it's not Samara, and that he loves her. Rachel responds "You're not my son." and sticks his body in to the water. Samara's hair comes out of Aidan's throat.
The bath successfully expelled Samara from Aidan's body, The water drains from the tub and Aidan is unconscious laying there. Rachel picks him up and cries "Breathe, breathe, I know it's you, please wake up!" . Then Aidan is coming back After that Rachel runs to the living room and says "You cannot have my son. "So, take me". Then, she willingly jumps into the TV. She finally succeeds to close Samara in the well and, after that, Rachel jumps off the cliff and ends up back in her living room with Aidan, where they embrace. Aidan calls Rachel '"Mommy"', and she asks him to just call her Rachel.