The movie begins with two teenage girls, Katie and Becca, chatting.
Becca starts to tell an urban legend about a video tape that will kill you if you watch it. Apparently, when you finish watching the tape you get a phone call saying you have 7 days to live. Katie got this horrified look on her face, she tells Becca that she and 3 of her friends watched a tape at a cabin (Important Later!) 7 days ago, almost to the hour. They got a phone call like Becca said. The girls went downstairs for something to drink, Becca went back up first. Katie was going up when the TV turned on. All that was on was static. Katie turned it off, but it turned on again. She finally unplugged the TV. She went up stairs and saw water coming out under her bedroom door. She slowly opens the door and sees that her TV is on. Briefly we see an image of a well (Important Later!), before the camera cuts to Katie screaming.
The next scene shows a boy, Aidan, drawing after class. His mom, Rachel comes to pick him up. He acts very mature and calls his mom by her first name. He says he will wait in the car while Rachel speaks to his teacher. The teacher inquires about how they are handling the death in the family three days ago. Katie was Rachel's niece and she used to baby-sit Aidan. The teacher shows Rachel some pictures Aidan drew, which showed a girl buried underground. Rachel says that is just Aidan's way of dealing, but the teacher said Aidan drew the picture a week ago.
We see Rachel getting dressed for Katie's funeral. Aidan had dressed himself and laid out Rachel's dress. At the gathering after the funeral, Katie's mom talked to Rachel. She said that she went to several doctors and no one can explain how a 16 year old girl's heart can just stop like that. She wanted Rachel to investigate, since Rachel was a reporter for a newspaper. Rachel initially was skeptical. She started to talk to some friends of Katie's and found out that Becca was in a mental hospital. She dug further, and discovered that Katie's 3 other friends all died that same night at the exact same time. She started to look at some photos Katie took from the cabin trip. The first few pictures were fine, but some of the later pictures had Katie and her friend's faces distorted.
Rachel decided to head out to the cabin. Outside we can see single tree on a hillside (Important Later!). Rachel talks to the caretaker, who says they frequently rent out videos since the TV reception is bad there. Rachel sees a tape among the rental that has no labels. She takes it and rents the same cabin Katie stayed in. She watches the tape at 5:15 pm, which shows the image of a ring. Some other images on the tape are a woman brushing her hair in front of the mirror, a bunch of dead horses on a beach, a centipede crawling across a table, a ladder against a wall, a burning tree, a woman falling to her death. When the video ends Rachel gets a call. A girl's voice says 7 days.
The next day, Rachel calls Noah and tells him about the tape. Apparently, Noah is a video expert. Rachel asks Noah to take her picture, and it comes out all distorted.
She shows him the tape. The phone rings but she doesn't pick up. Noah tells her to make a copy and he'll look through it. Rachel does and they use Noah's video equipment to explore the images. Rachel finds that there is an image in between frames, which turns out to be a lighthouse. She goes through the archives and discovers the lighthouse was located on Moesko Island. Rachel then found out the identity of the woman in the mirror. She was Anna Morgan, who owned a horse farm with her husband Richard on the island. Apparently the horses went crazy and all jumped into the sea and drowned. Anna was admitted to a mental hospital and eventually committed suicide. In the meantime, Rachel has a horrifying dream. She sees a girl sitting in a puddle of water in her room. The girl's face is covered by her long hair. She grabs Rachel's arm and we see flashes from the Ring video. Rachel wakes up, and she has a bruise on her arm in the shape of a hand.
Rachel wakes into her living room, she is horrified by the fact that Aidan is watching the tape copy she made.
The phone rings, but Rachel hangs up. She calls Noah and tells him that their son saw the tape. Now they have an urgency to solve the mystery, especially since Rachel has only two days left. Rachel leaves for the island on the tape and Noah heads for the mental hospital where Anna stayed. On the ferry to the island Rachel sees a horse in a trailer. She tries to pet the horse, but it starts going crazy. The horse broke free from the trailer and ran straight off the ferry. It was chopped up by the propellers. Meanwhile, Noah went through the records for Anna and discovered a separate file for a Samara Morgan. Turns out that Samara was the Morgan's daughter.
Rachel was still searching through her collection of archive files and also finds out about Samara. When she reached the island she questioned Richard Morgan about it. Richard was very distant and refused to talk about it. Rachel then went to the island doctor, who has been on the island her whole life and knows everyone. She says that Anna and Richard tried to have a child for years but was unsuccessful. One day, they left the island and came back with Samara. Apparently the mother died at childbirth and they adopted her. The doctor seems hesitant to talk about her, except to say that a lot of bad things happened on the island. And when Samara disappeared it got better. Back at the hospital, Noah discovered that there is a video recording of Samara's sessions. He went to take out the video, but it turns out that it was missing. The last person to take it out was Richard Morgan. Noah rushed to the island to warn Rachel.
That night Rachel went back to the Morgan farm. The door was open so she went inside. She found a tape in the vcr, which turned out to be the sessions with Samara. We see that Samara never sleeps, and she says cryptic things like, "I want to hurt everyone." Rachel turns around to see Richard. He has a lot of power cords wrapped around him. He takes the TV and goes upstairs. Rachel follows him to see that he has plugged electronic equipment in the bathroom and flooded it with water. Richard says Samara will never stop and turns everything on, electrocuting himself. Just then Noah runs into the house. They go into the barn, and found Samara's room. There was something behind the wallpaper. When they peeled it away, it turned out to be a drawing of a tree identical to the one on the video. Rachel figures out that the tree is the tree near the cabin, so they rush to the cabin the next day.
By then, it is very close to the time Rachel saw the tape the first time. Rachel says that it is too late for her, and that Noah should try to save Aidan. In frustration, Noah knocks over a jar of marbles. They roll to the same spot and form an arrow. Noah takes an ax and smashed up the floor boards. Beneath the cabin was a well. While Noah and Rachel looked at the well, the TV turns on to snowy static. Water starts to come out of the TV set and the nails on the floorboards starts to unravel. Suddenly, the floorboards crash, sending the TV set sliding into Rachel, knocking her into the well. In the well, a hand grabs her and Rachel gets a vision. She sees Samara standing in front of the well back when there was no cabin. Anna came up behind her and suffocated her with a bag. Then she dropped her into the well. But Samara was still alive. As she looks up she sees the well being sealed. The light edge around the seal is the ring from the video. Rachel snaps out of her vision and sees Samara's body. By then, Noah had called the police and they are rescued. Rachel says it is over. She rolls up her sleeve and the bruise on her hand disappeared. Noah says he can't imagine how long a person can live inside the well, Rachel says 7 days. Noah and Rachel seemed to grow closer due to the ordeal and are ready to begin a relationship.
The next morning Rachel watched Aidan wake up. Aidan asks Rachel what happened. Rachel said everything was okay, and she had found the little girl. She was going to get a burial and everything would be better. Aidan became agitated that Rachel helped her. He said that she wasn't suppose to help her. He said she will never stop, and she never sleeps. Rachel sees that a bruise was on Aidan's arm. She tries to call Noah to warn him.
The TV at Noah's place turns on to a static signal. Noah turns it off, but it turns back on to the image of a well in the forest. Water starts to come out of the TV set. Suddenly, a girl starts climbing out of the well. Her hair is in front of her face so we can't see her face. She comes closer and closer toward the screen. In one horrifying moment, she climbs through the TV screen into Noah's apartment. Noah backs away in terror while she comes closer. Then, she looks up and we see the decayed face of Samara Morgan.
The movie cuts to Rachel rushing to Noah's place. She arrives to see Noah's decomposed body lying in the apartment. She runs home and thinks about what she did differently that spared her life. She remembers that she made a copy. Rachel makes Aidan make a copy of the video and tells him it will be alright. Aidan asks what will happen to the person they show the video to, and Rachel just stares at the screen.
The last shot is of tv static, and then rapid succesion of images from the ring video.