Insidious is a movie that has been the source of nightmares for many. When a family consisting of a mother, father, and their three children move into a new house in a new town it does not take long for things to go inexplicably wrong. Just a few days after their move, the Lambert's son, Dalton, falls into a coma like state and does not wake up. After months in the hospital the Lambert family brings Dalton home, although he is still in the coma.
Upon the family's arrival, supernatural events ensue. The woman of the house, Renai, starts to see strange people in her home. Upon Renai's request, the family uproots again and moves into a new house, but the supernatural events do not cease, and they turn violent. The family brings in a woman who specializes in mediating supernatural events. The family and this hired professional eventually come to the conclusion that the family's son, Dalton, is trapped in a place called "The Further". The hired professional, Elise, explains that there are several demons fighting for control over their son Dalton's body. This was able to happen because Dalton can do something called "astral project". This means that while he is sleeping he is traveling into different worlds but he thinks that these different worlds are just dreams. In this particular case, there is one incredibly powerful demon fighting multiple other demons for the control over Dalton's body. The demon watches over Dalton waiting for the time when it is possible to take over Dalton's body completely.
After Elise's evaluation, she pulls Dalton's parents aside and reveals some shocking news. Dalton's father, Josh, was also able to astral project when he was a child. He was plagued by the spirit of an old demonic woman who would present herself when photos were taken of Josh. The two parents decide that, based on Josh's ability to astral project, Josh should astral project into "The Further" in order to find his son and bring the boy back with him safely. He finds his son and they make their way to escaping, when Josh is faced with the old woman that plagued him as a child. He tells his son to go ahead so he can confront this woman. The two boys wake up, but the horror is not yet over. Josh has been possessed by the old woman that was after him as a child.