Insidious (2010) is a supernatural horror film directed by James Wan and written by Leigh Whannell. It is the first installment in the Insidious franchise, which has since become one of the more popular modern horror series.

The story follows the Lambert family, particularly their son Dalton, who falls into an inexplicable coma. As supernatural events begin to plague the family, they discover that Dalton has the ability to astral project while asleep and that his spirit is trapped in a dark realm called “The Further.” The film focuses on the parents, Josh (Patrick Wilson) and Renai (Rose Byrne), as they try to save their son, eventually turning to a psychic and a team of paranormal investigators.

Insidious is known for its chilling atmosphere, jump scares, and eerie sound design. It revived interest in the haunted house sub-genre and helped solidify James Wan as a modern horror filmmaker, leading to other successful films like The Conjuring.

The film was praised for its effective tension and scares, though some critics felt that the third act, which delves more deeply into “The Further,” became less frightening than the buildup. However, its unique approach to the supernatural and the introduction of a metaphysical world made it stand out in horror cinema.