During the "Obama era" we saw quite a few horror films focus on supernatural occurrences and on families in peril, perhaps inspired by the success of the "The Amityville Horror" remake in 2005. Whereas 1973's "The Exorcist" and 1985's "Nightmare on Elm Street" featured broken, single-parent families facing off against supernatural evil, "Insidious" and quite a few other movies like it have intact, albeit struggling, families pitted against supernatural forces.
There was one film from the '80s that did have an intact family battling supernatural forces: Steven Spielberg's "Poltergeist". Obviously inspired by that film, James Wan crafted a similar update for the 2000s. Basically a de-Spielberg-erized "Poltergeist" that made about as much money adjusted for inflation at the box office, "Insidious" proved that the nuclear family-vs.ghosts formula was a winning formula for the second decade of the 2000s. The movie spawned a sequel and certainly provided inspiration for the even edgier "Sinister" a year later.
Like "Sinister", "Amityville Horror", and "Poltergeist", "Insidious" opens with a family moving into a new home and, after some character development and natural tensions between the matriarch (Rose Byrne) and patriarch (Patrick Wilson) of the house, supernatural happenings slowly start happening: a strange door opening here, a noise there, a creepy ghost kid in a wardrobe closet -- those sorts of things. Standard fare delivered effectively by "Saw" director James Wan and an amazing horror score by Joseph Bishara, who also plays a role in the film as a malevolent spirit.
Things take a sudden turn toward the nightmarish when the family's oldest son goes into a coma for no apparent reason. As the hauntings increase, the family decides the problem must be that their new home is haunted, and decide to change addresses, moving into a less haunted-feeling, smaller place. Of course it doesn't come close to fixing their problems, as one particular haunting -- involving very effective use of the song "Tiptoe Through the Tulips" by Tiny Tim, an unintentionally creepy '60s song that seemed destined for prominent placement in a horror film at some point -- convinces the mother that something needs to be done to rescue their family. Enter the grandmother (played by Barbara Hershey of "The Entity") who hooks the family up with a psychic and a pair of professional ghostbusters, who provide some badly needed comic relief toward the middle of the film.
The best thing that James Wan directed up to this point in his career, "Insidious" is a stylish, well-acted, and emotionally compelling PG-13 horror film, and a pretty important one given how well it did at the box office. Wan followed it up with the scarier and similar "The Conjuring," a movie that was a lot like this one, but that focused much more on the ghostbusters of the story, and with an "Insidious Chapter 2" that didn't live up to the expectations of the original.