The Ring Two is the sequel to The Ring and continues directly after Rings. After the first film's events, Rachel Keller and her son Aidan have left Seattle and moved to Astoria, Oregon to start a new life. However, the past comes back to haunt them when Rachel comes across a victim of Samara Morgan's cursed videotape. After destroying the tape, Rachel begins noticing Aidan displaying strange behaviour, leading to his eventual hospitalisation after he contracts what may be pneumonia. It quickly becomes clear that Samara has a role to play in Aidan's suffering, leading Rachel to investigate Samara's origins beyond the Morgan Ranch and stop the girl for good.
Naomi Watts and David Dorfman reprise their roles as Rachel and Aidan, with Kelly Stables portraying Samara while imagery of Daveigh Chase is still used for facial shots. New cast members include Simon Baker, Elizabeth Perkins, Gary Cole, and Sissy Spacek.
At the end of The Ring, Rachel and Aidan Keller made a copy of Samara Morgan's cursed videotape and passed it on to someone else. Several months on, the tape has since created a teenage cult across the region. In Astoria, Oregon, a boy named Jake attempts to show his copy of the tape to his friend, Emily. Retreating into his kitchen after starting the tape, Jake thinks he's safe until he spots water flooding the kitchen and runs into the living room to discover Emily hasn't watched the tape but covered her eyes out of fear. Jake collapses in front of the television as Samara appears out of her well and kills him with Emily watching.
Rachel and Aidan have since moved to Astoria. Rachel now working for the local newspaper run by Max Rourke. Aidan regrets unleashing Samara's curse into the world but Rachel believes it was the best thing to do, since Samara's curse killed Aidan's father Noah Clay and cousin Katie Embry in the first film. Rachel learns from her fellow journalists of Jake's body being reported on a police radio, and she grows concerned with the description. Arriving at the crime scene, Rachel sneaks into the back of an ambulance and finds Jake's body - he has a deformed face. As she tries to zip up the bodybag he is in, Samara pops up out of the bodybag and reveals she has been looking for Rachel before disappearing. After learning the tape's location from a traumatised Emily, Rachel destroys the tape in a flaming oil barrel, asking Samara not to harm her. Unfortunately, this unleashes Samara's spirit as it flees to a television in Rachel's house.
Aidan awakens and goes downstairs to turn the television off, only for Samara to appear onscreen and drag him into the TV. Aidan wakes up in bed realising it was a nightmare. Rachel arrives, finding Aidan has apparently wet the bed. Later, Rachel picks up a distant Aidan from school and they drive to a fair outside a local church. Aidan wanders off with a camera, but is disturbed when several deer in a field look up to his presence. He wanders into a public toilet where he sees Samara standing behind him in the shadows. He takes photos of himself in the mirror as Rachel comes in and finds he has suddenly become physically cold. She drives him home and asks if Samara has been in his nightmares. He is unable to answer as Rachel is forced to hit the brakes when a deer appears in the road. It walks on past only to turn around and attack the car, followed by several other deer. The car is eventually surrounded by deer, but Aidan looks at one of the deer, causing the group to back away and Rachel makes her getaway.
By evening, Aidan's health has deteriorated further and Rachel guesses he may have pneumonia. The power goes out, so Rachel checks on Aidan. Hearing a scratching noise, she turns and sees Samara across the room digging into the wall with her hand. Rachel goes to Aidan, but finds him missing from his bed, now standing where Samara was. The hole Samara has left suddenly turns into a burnt image of the tree on Shelter Mountain, causing Rachel to flee to her workplace with Aidan. Max shows concern and takes the two to his house where Rachel puts a defiant Aidan in a bath. She returns home briefly to find photos on Aidan's camera, revealing Samara has possibly possessed Aidan.
Max tries to check on Aidan, but is unable to unlock the bathroom door. Rachel runs in, as Max is running off to find something to break the door down with. Rachel manages to kick the door, but finds all of the bath water now floats in the air and Aidan is being held by Samara. Rachel grabs Aidan, who snaps back into reality, causing all the water to fall to the floor. Aidan disappears in the bath, Rachel dragging him out only to pull out Samara instead, who refers to her as "Mommy". Rachel pushes her underwater, but as Max runs in, it looks like she is trying to drown Aidan. Max helps pull Aidan out and forces Rachel to take him to the hospital. In the hospital, Rachel sits by Aidan's bedside where he lies unconscious. However, he suddenly grabs Rachel's arm and channels a series of images into her head. Rachel has no time to contemplate them as Doctor Emma Temple enters and quickly makes it clear that she believes Rachel is a threat to her son after suffering from postpartam depression after giving birth to him and sends her out.
A frustrated Rachel tells Max of Samara's origins and asks him to keep an eye on Aidan as she leaves. Rachel decides to investigate the images Aidan sent her, so she ventures out to Moesko Island and to the Morgan Ranch which is up for sale. After speaking with a dodgy retailer Martin Savidge, Rachel ventures into the house's basement where she finds a trunk filled with objects including a photo album containing a photo of Samara with her birth mother. Meanwhile, Aidan awakens in hospital now fully controlled by Samara. Desiring to see her "Mummy", Samara kills Dr. Temple by making her commit suicide via a lethal injection and wanders around until she reaches Max's house.
Rachel visits a carehome run by nuns, used by young mothers for birth. The head nurse, Sister Elizabeth, explains to Rachel that Samara's mother is Evelyn,but had problems with her daughter; she never cried, aside from when she tried to bathe her and assumes that Evelyn believed the dark waters of the afterlife were coming to kill her daughter. In a flashback, it is revealed that Evelyn tried to drown Samara in a pool outside, but was stopped by the nuns. Samara was put up for adoption, and Evelyn went to an asylum. Rachel visits the asylum and meets Evelyn, who cryptically warns her that Samara must be exorcised from Aidan.
Max returns home and finds Aidan/Samara waiting for Rachel. He quickly grows suspicious and tries to sneak a photograph of Aidan, but he is caught. Rachel returns to Max's house, but finds him missing and Aidan who is thrilled to see her. Rachel also realises Samara is in control of Aidan when she accidentally calls her "Mommy". Rachel spots Max's pickup truck outside, where she finds him dead at the steering wheel. Rachel hides herself in a bedroom and falls asleep, where Aidan talks to her in a dream and instructs Rachel to put him in the bath to remove Samara. Rachel drugs Samara, placing Aidan's body into the bath which causes Samara to flee Aidan.
However, Samara appears in the TV and Rachel allows herself to be pulled into the monochromatic world of the video. Finding herself in the well, Rachel spots the cover is open and begins to climb the well. Samara realises this and emerges in her true demonic form, climbing up the wall like a spider only to be knocked back down when Rachel kicks out a brick, causing water to knock Samara down. Rachel climbs out of the well as Samara climbs back up, shouting for her "Mommy", only for Rachel shout she isn't her mother and slams the cover shut. She wanders towards a cliff following Aidan's calls, and sees an image of Anna Morgan falling off the cliff, and does likewise, but awakens in Max's house with Aidan, the two reunited.
- Naomi Watts as Rachel Keller, a journalist who must deal with Samara's restless spirit once again.
- David Dorfman as Aidan Keller, Rachel's son who is possessed by Samara.
- Simon Baker as Max Rourke, Rachel's boss at the news room she works at.
- Kelly Stables as Samara Morgan, the antagonist of the film. A little girl whose spirit lingers on in a cursed videotape. Archive footage of Daveigh Chase is used.
- Elizabeth Perkins as Doctor Emma Temple, a doctor and child psychologist.
- Gary Cole as Martin Savide, a dodgy retail agent trying to sell off the Morgan Ranch.
- Sissy Spacek as Evelyn, Samara's disturbed birth mother.
- Ryan Merriman as Jake, a victim of the tape.
- Emily Van Camp as Emily, Jake's friend.
- Mary Joy as Sister Elizabeth, a nun who prevented Evelyn from killing Samara as a baby.
- Mary Elizabeth Winstead cameos as a young Evelyn.