The Grudge series focuses on those affected by a curse created in a house in Suginami by a deceased family's rage that destroys the lives of everyone who comes in contact with it. Known as "the ju-on," this curse causes its victims to become fatally afflicted with it, which in turn leads to a new curse being born and passed like a virus to all those who enter the family residence or come into contact with the curse in any way.
''The Grudge'' describes a curse that is born when someone dies in the grip of a powerful Rage (emotion) or extreme Suffering. The curse is an entity created where the person died. Those who encounter this supernatural force die, and the curse is reborn repeatedly, passing from victim to victim in an endless, growing chain of horror. The following events are explained in their actual order; however, the film is presented in a nonlinear narrative.
In Japanese society, it is said a curse is created when a person dies in the grip of a powerful rage (emotion) or sorrow. Those who encounter the evil supernatural force are consumed by it, the curse is born repeatedly and spreads. The original victims of the curse, the Saeki family, haunt their Tokyo suburban house as ghosts and kill anyone who enters. Housewife Kayako Saeki was murdered by her husband Takeo Saeki after he discovered she infatuated to another man, their son Toshio Saeki and pet cat Mar also being murdered, before Takeo was hanged by Toshio’s ghost. In the first film, American social worker Karen Davis tried to burn the house down to stop the curse, but failed, finding herself hospitalised and haunted by Kayako. The film's chronology is told in a non-linear fashion, taking place in 2004 and 2006 respectively.
Jake Kimble (the only survivor from the second film) is under the care of Dr. Sullivan in an asylum. He is locked in his room following several escape attempts and is attacked by Kayako. The attack is seen on security cameras, although Kayako cannot be seen, and Jake is dead by the time Sullivan arrives with a security officer. News of the incident reaches a young woman in Tokyo, Naoko, who is the sister of Kayako. Believing that her sister is responsible, she travels to Chicago.
An investigator follows the trail of a grisly case back to a cursed house harboring a tangled, gruesome history — and an ugly, boundless rage.