There is a great deal of prowling motion in Insidious: a recurring sideways dolly outside a haunted house, a trench-coat-clad cacodemon pacing outside a second-story window. It's the restless motion of a movie stalking its preyyou, dear viewer. Patrick Wilson and Rose Byrne are moving their family into their new home when one of their boys, Dalton (Ty Simpkins), drops into a medically inexplicable coma. As symptoms of haunting pile up, director James Wan and screenwriter Leigh Whannell, who collaborated on Saw, smartly maintain a measured ratio of supernatural to everyday horror (a couple noticing together that they are no longer quite young, Dalton's nurse explaining the workings of a gastro-nasal feeding tube). Wilson and Byrne make a believable stress-fractured couple, even if their performances lack the harrowing psychological detail of the genre's best, while Insidious contains more prickly, scalp-crawly moments than any American horror movie in immediate memory. The things going bump in the night are often familiar from other movies, and the film's last third gets rather silly-surrealist. But though we need visionaries, we also need solid craftsmen who seem to enjoy their work. Insidious is the product of the latter. It doesn't build a better haunted house but, when on its game, reminds us of the genre's pleasures.