The first shot of "Insidious" displays the screen-spanning opening credit, "A James Wan Film," in large, bold letters the viewer can't miss. At the end of those same titles, "Directed by James Wan" lingers for several beats longer than the norm. Prominently advertising himself with the sort of event-like fervor that would make even M. Night Shyamalan blush, Wan has had a hit-and-miss track record with his films up to this date (2004's "Saw," 2007's "Dead Silence," and 2007's "Death Sentence") and hasn't really proven what the credits slyly suggest: that a master filmmaker of noted importance is in charge. Roughly 100 minutes later, Wan has still not quite earned the film's self-congratulatory fanfare, but he has moved closer to displaying just how astute he can be at working his audience to a fever pitch. As uneven as "Insidious" sometimes is, it can also be dread-inducingly, cling-to-your-armrest scary. Wan and his resident screenwriter-actor, Leigh Whannell, may still need to work on building characters and seeing stories through to a satisfying conclusion, but as a vessel that mischievously provides some seriously petrifying images and roughly five huge jump scares spread throughout, the film does its most important job—to set audiences on edge—admirably.

Aspiring musician Renai (Rose Byrne) and school teacher Josh (Patrick Wilson) have just moved with their three kids to a spacious, attractive, somewhat creaky new house. It should be a fresh start for all of them, but then their intuitive eldest son, 8-year-old Dalton (Ty Simpkins), falls into a sudden coma that leaves the doctors baffled by its cause. This would be a stressful, upsetting time for any parent in the same situation, but it's made all the worse when Renai is soon overwhelmed with unexplainable occurrences and frightening visions of people lurking with her in the house. Non-believer Josh reacts by withdrawing into his work until Renai puts her foot down and insists they leave. Mistakenly believing their problems are finally behind them, the couple soon discover, with the help of medium Elise Rainier (the underrated Lin Shaye), it wasn't their house that was haunted, but their son.

A ghost story with a set-up that matches scene for scene the apparent blueprint of the genre, "Insidious" tries to fool the viewer into thinking that the characters and the lives they lead—Renai's music-writing and piano-practicing, for example—are more important than they really are. The pacing is slow and measured at first, biding its time until it's ready to pounce. When it finally does, it startles with its sheer abruptness and force and hauntingly simple mise en scene. Suddenly transformed into what it genuinely is, the film stops paying much interest to the people and becomes all about the scares. Because they usually work like gangbusters and aren't just unimaginative throwaways, that's not necessarily a criticism. A large portion of the picture, especially in its superior first half, repeats the formula of a character—usually Renai—walking down hallways and peeking in rooms. Most of the time there is nothing there. When there is, it is so effective it is sure to elicit jumps, if not screams, in the nervous audience. Were that not enough, director James Wan unforgettably incorporates Tiny Tim's "Tiptoe Through the Tulips" into the proceedings in a way that is goosebump-forming and possibly genius. Tiny Tim's legacy might not have been to terrify the living hell out of people, but that is what it will be once this movie gets done with him.

Lest it be assumed that the picture will continue following a predictable plot, Wan and screenwriter Leigh Whannell do, to their credit, concoct story motives and a third act that diverge from typical haunted house movies. Astral projection, demons, and a dark realm called The Further all figure into the mix, but so do two ghostbusters (Angus Sampson, Leigh Whannell) who ought to have been excised. The fantasy-laden dip into the subconscious near the end is more ambitious than wholly successful, but remains visually interesting and at least different. For a film that partially works so well because of its use of practical effects, make-up, and costumes over a reliance on CGI, one shot involving a creature climbing sideways on a wall instantly dissipates the intensity and takes the viewer out of the situation. Without giving things away, a last-scene twist is also misguided in its identity reveal of a certain character.

"Insidious" is akin to a particularly macabre funhouse ride, the viewer (in the place of the passenger) taken on a tour where the threat of spooky things popping out at any second doesn't alleviate until it's over. The achievement in boasting a high scare quotient evens out the movie's numerous trouble spots. Patrick Wilson (2010's "Morning Glory") is trifled by murky motivations as Josh, a skeptic even when it's blatantly obvious something supernatural is going on. He is outacted by Rose Byrne (2010's "Get Him to the Greek"), committed and believably frantic as her Renai starts seeing things she can't believe, yet can't deny. While son Dalton plays an important role in the goings-on, their other two kids all but disappear by the second half, leading one to wonder why they were put in the screenplay at all. Barbara Hershey (2010's "Black Swan"), too, is wasted as Josh's worried mother, who has had her own recent experience with a specter in her dreams. When "Insidious" is just concentrating on empty spaces and the propensity for something nightmarish to be lurking about, the film is exceptionally good. When director James Wan tries to open the scope up, introduce more characters, and expand the mythology, its focus tends to get lost now and again. The real story is and should be the one about the average family whose lives are threatened and psyches left unhinged by forces greater than they can imagine. It is this little corner of the unknown where actual fear and dread reside, and Wan knows that all too well.