The film Insidious follows the story of Josh and Renai Lambert, a married couple with three children. After moving into a new home, their eldest son Dalton falls into a mysterious and inexplicable coma-like state. While doctors are unable to diagnose or treat his condition, strange occurrences begin to happen around their house, leading them to believe that they may be dealing with a paranormal entity.
Desperate for answers, they enlist the help of a psychic medium named Elise, who discovers that Dalton's spirit has in fact left his body and is now wandering the astral plane, a dangerous place inhabited by malevolent entities. Elise agrees to help reach out to Dalton and bring him back, but warns them that they are dealing with something much more powerful and evil than they realized. As they delve deeper into the mysterious realm of the afterlife, they uncover dark secrets and terrifying truths about their family and the past that threaten to consume them all.
Insidious was directed by James Wan and written by Leigh Whannell, and became a critical and commercial success upon its release in 2010. It spawned three sequels, and is widely considered to be a modern horror classic.