Katie Embry (Amber Tamblyn) and her friend Becca (Rachael Bella) are having a sleepover in Becca's home in Washington. Becca recounts the story of a supposedly cursed videotape. Anyone who watches the tape gets a mysterious phone call and then dies seven days later. Katie reveals that she had watched the tape the previous week. The phone rings, startling the girls, but it is only Katie's mom. After talking with her mother, Katie returns upstairs and sees an image of a well on her TV screen and screams and in the process, her face distorts. Katie ultimately dies of a heart attack under mysterious circumstances.
Rachel Keller (Naomi Watts) is a journalist living in nearby Seattle. She goes to pick up her young son, Aidan (David Dorfman) from school and finds out from his teacher that he has been drawing disturbing pictures of his cousin Katie's mysterious death, some of which mysteriously predated it. They later attend her wake where Rachel finds out from her sister Ruth, Katie's mother, how she found her daughter's distorted corpse with a look of pure horror on her face and asks Rachel to investigate the strange circumstances in which Katie died. Rachel discovers that the people who saw the video with Katie died on the same night and same time as her. She also finds out that the only witness to Katie's death, Becca, is now in a psychiatric hospital. Rachel then goes up to Katie's room, where she discovers a scrapbook of Katie's with cropped out pictures of people with their faces scratched out. She takes a photography pick up slip and goes home.
The following morning, Rachel goes to pick up the photographs and discovers the faces of all those who died were distorted in the most recent pictures. Her investigation leads her to the cabin where Katie and the others watched the tape. Rachel finds and watches the tape, which includes footage of a well. The phone rings, and she hears a child's voice say "seven days." The next day, Rachel calls Noah (Martin Henderson), her ex-boyfriend, to show him the video and asks for his assistance. He asks her to make a copy and she does.
After viewing the tape, Rachel begins experiencing nightmares, nosebleeds, and surreal situations. She watches the video again, clip by clip, and a fly from inside the tape manages to leave the television screen. Rachel visits Becca in the mental hospital and when Rachel asks her what happened, Becca answers "She will show you" and reminds Rachel that she has four days left. Rachel investigates the tape more and finds out about a horse ranch owned by Anna Morgan and her husband Richard and their adoptive daughter Samara. The horses at the Morgan ranch went mad and drowned themselves, which supposedly caused Anna, a horse-lover, to become depressed and commit suicide. Rachel is later horrified to discover that her son has watched the tape. When the tape finishes, an arm reaches out of the well. Panicked, Rachel calls Noah, revealing that Noah is Aidan's father.
Rachel goes to the Morgan house and finds Richard, who refuses to talk about the video or his daughter. A local doctor tells Rachel that Anna could not carry a baby and adopted a child named Samara (Daveigh Chase). Dr. Grasnik (Jane Alexander) recounts that Anna soon complained about gruesome visions that only happened when Samara was around, so both were sent to a mental institution. Noah goes to the mental institution and finds Anna's file. He discovers that there was a video of Samara, but the video is missing. Rachel sneaks back to the Morgan house where she discovers a box containing the missing video. She watches it and is confronted by Richard, who claims that she and her son will die, and that there is nothing they can do. He commits suicide in front of Rachel by using an electric cable in a bathtub.
Rachel and Noah go to the barn and discover the attic where Samara was kept by her father. There is an image of a tree near the cabin burnt into the wall. They return to the cabin and discover that it was built on top of the well. Rachel falls in and finds Samara's skeleton. She has a vision, which reveals Anna suffocated Samara with a plastic bag and pushed her into the well. However, Samara did not die from suffocation and survived in the well for seven days. Noah informs Rachel that the time she should've been killed has passed, causing Rachel to believe that setting Samara free from the well broke the curse.
When Rachel informs Aidan that they will no longer be troubled by Samara, he is horrified and tells his mother that Samara "never sleeps" and they were not supposed to help Samara, just as his nose begins bleeding. Rachel realizes Noah will be the next to die and drives to his apartment. While she does, Noah's television switches on and a decaying Samara with hair covering her face crawls out of the screen. Noah soon dies of fright as he sees Samara's eye. Rachel discovers his body with a terrified and discolored face similar to Katie's. Rachel returns home and burns the original tape. She recalls the footage of Samara in the mental hospital and realizes that Samara was truly evil. Rachel wonders why she did not die like the others, and remembers that she made a copy of the tape. She realizes the only way to escape the curse and save Aidan is to have him copy the tape and show it to someone else, thereby continuing the cycle of death as Samara intended.
Reference
https://en.wikipedia.org/wiki/The_Ring_(2002_film)