Rose Byrne, Patrick Wilson and their three young children have just moved into a big, old home.  He's a teacher and she doesn't work, so immediately I assumed there was some deal with the devil to make the down payment, but this was just my mind playing tricks.  The young baby does nothing but cry and one night the eldest sees something, makes a spooky face, then goes to sleep and NEVER WAKES UP.

He's not in a coma, he's just. . .in limbo.  Rather than making the cover of the New England Journal of Medicine with this indescribable condition, they just send the kid home.  And then the craziness starts.
I can't lie, the first few scares got my heart rate up.  There are demonic sounds on the baby monitor and, even though I was thinking "here comes the scary part, here comes the scary part" when something finally jumped out, I yelped like a frightened puppy.
I can't recall seeing a movie that relied as heavily on loud, dissonant piano notes on the sound track as much as Insidious.  Director James Wan (the first Saw movie and follow-up garbage he'd rather you not remember) either doesn't trust us or doesn't have the chops to allow creative framing or tense perspective shots to deliver the scares.  Either way, I found I did most of my crying-out not because anything truly frightening was happening on screen, but because something REALLY LOUD JUST CRASHED IN MY EAR.
I certainly wasn't involved in the plot in any way, which is a shame, because I think a comotose, house-bound child is fertile soil from which a genuine horror film can grow.  After Byrne sees enough weird visions she gets the family to relocate.  The scares keep coming in house two, making us all wonder what the hell kind of realtor they're using.
There's a twist, of course, and a too-late attempt at humor in the form of some goofy ghost hunters.  Once the "truth" is revealed, however, only the audience members willing to suspend their disbelief to the point they could wrap it around the circumference of Jupiter will keep from checking out.
So this is what's in store for you in Insidious: a real moronic supernatural horror film that exploitatively uses startling tactics to get in four or five decent jump scares.  If you are a high school kid on a date, go see Insidious.  If not, go take a run or finish that Dostoyevsky novel you keep putting off.