A family looks to prevent evil spirits from trapping their comatose child in a realm called The Further.

Insidious is a horror film split down the middle: in its first half, a haunted house movie in the style of a domestic drama; in the second half, an exorcism/ghostbusting movie that indulges in lots of humor and spooky, surrealistic dream sequences. There are some interesting ideas at work in the film, although it is inconsistent scene to scene; sometimes Insidious plays like a sincere, naturalistic family drama, and other times director James Wan employs sudden cuts and time lapses that contribute to forced melodrama and contrived plot twists.

Josh (Patrick Wilson) and Renai (Rose Byrne) have just moved into a new house, looking for a fresh start. They're parents to Dalton (Ty Simpkins), a cute kid who, true to horror movie form, soon seems to become "possessed" by some malevolent force inside the house. The boy falls into a coma for which doctors have no explanation. Renai, well played by Byrne as the typically stressed mother of a young child and wife to a sweet but oblivious husband, soon begins hearing scary noises and seeing unexplained figures creeping around the house. To Wan's credit, the horror in this first half is revealed slowly, building tension and taking the time to establish the domestic routine of the family.

Convinced the house is haunted, Renai and family pack up and move again. (Producer Oren Peli, of Paranormal Activity fame, clearly has a penchant for putting people in giant houses they could never afford. Josh is a teacher and Renai is a stay-at-home songwriter, they have three young children, mounting medical bills, and yet they managed to move houses twice in three months!) Things are no better in the new house, however. It becomes increasingly clear that the offending ghosts and demons weren't tethered to a place, but a person--their son Dalton.

Josh and Renai finally call in some experts, a pair of nerdy, bickering ghostbusters (played by Angus Sampson and writer Leigh Whannell), and Elise Rainier (Lin Shaye), an expert on paranormal activity and an old friend of Josh's mother (Barbara Hershey in a fairly thankless role). In a long expositional monologue, Elise explains Dalton's condition with a lot of mumbo jumbo about astral projections, "Travelers" and a nebulous miasma she terms "The Further." Lin Shaye has a lot of work to do in the scene convincing both Dalton's parents and us of the validity of these techniques, and the actress, with her earnest air and grandmotherly warmth, pulls it off nicely.

The exorcism scene starts strong, with some comedic interplay between the ghostbusters, Elise, and the tense and nervous parents. It reminded me a bit of the films of Sam Raimi in the way in which comedy and horror are blended. Unfortunately, Wan and Whannell don't fully commit to the comedy and the scene takes a turn into familiar horror movie tropes. A distracting strobe effect and disorienting editing ratchet up the visual mayhem, but not the terror, as the spirits from "The Further" cross-over into the physical world and begin attacking our heroes.

The exorcism having been unsuccessful, Josh must rescue Dalton himself. This following sequence is probably the most effective in the movie. Josh travels into "The Further" and we follow him as he passes one nightmarish tableau after another. Josh's progression from scene to scene--here he sees Dalton, here he sees a family of ghosts dressed in old-fashioned garb--recalls the experience of walking through a Halloween maze, complete with eerie candles and spooky haunted house fog. Director Wan takes great pleasure in staging scenes with expressionistic lighting (coming from Josh's electric lantern), copious smoke, and black, blank space. Once Josh finds Dalton in the devil's lair, we're treated to something truly weird and wonderful. The devil's digs are something like a cross between The Phantom of the Opera and a Prince music video: baroque surrealism with more than a little David Lynch influence. Wan is clearly working with horror movie cliches here: the ghost of an old woman in the wedding dress and the old-timey family are straight out of Disneyland's The Haunted Mansion. The sequence was my favorite in the film by far, and I wish the film had more of its innovative weirdness.

Insidious has ambitious within its genre, and certainly its more hallucinatory moments are interesting. Unfortunately, there's a last-minute reversal in the film's closing seconds that is rushed and cliched. Of course, a film of this kind cannot end happily; that would actually be original. And, of course, the filmmakers must make room for the possibility of a sequel.

Insidious has two or three genuine jolts of fright, but it fails to provide a lasting impression of terror or a single memorable or iconic image. Director James Wan seems a bit conflicted. He is treading on overly familiar ground with the standard "scary face in the window" and "the ghost is right behind you!" scares, each punctuated by a conspicuous music cue (hysterical strings and thudding piano). Everyone knows these scares are coming and after the first few, they lose their impact entirely. There's only so many times I can see a ghost or a devil until they become familiar and non-threatening. And the familiarity, even intimacy, with these otherworldly creatures is clearly part of Wan and Whannell's intent. It's a film about a family unit confronting its internal demons, literally and metaphorically. But as these themes are hit again and again, the terror wears off.

The latter half of the film, it seemed to me, almost stops trying to be scary at all. The more traditional scares in its first half are supplanted with campy, fun house spooks, goblins, and ghost-hunting shenanigans. The characters of the two nerdy ghostbusters supply comic relief that clashes with Josh and Renai's agitated urgency. It's not an entirely unwelcome tonal shift, but I had a hard time taking the demon seriously as a threatening presence with so much humor in the script.