Much of what makes "One Hour Photo" click is the casting.
Robin Williams is probably the last person you'd expect to play a lonely photo clerk who becomes psychotically obsessed with a family whose pictures he develops. This is Patch Adams, after all. This is Mrs. Doubtfire. This is Mork from Ork - he couldn't hurt anyone, right?
Wrong. As middle-aged drone Sy Parrish, the normally sunny Williams is genuinely, believably creepy. And putting nearly any other actor in the role wouldn't have produced such a chilling effect.
"One Hour Photo" is the third film this year in which the manic comedian has shown a darker side, following the overbearing "Death to Smoochy," in which he played a corrupt kids' show host, and the moody "Insomnia," Christopher Nolan's follow-up to "Memento," in which Williams played a cold-hearted killer.
Here, he shows a desperate unpredictability that we've not seen before, which makes this his scariest performance yet.
It also helps a great deal that writer-director Mark Romanek has such an eye for visual imagery. A former music video director for artists including Madonna and Nine Inch Nails, Romanek gets the most out of every shot by using extreme minimalism, a starkness that matches Sy's infinite neediness.
Sy doesn't have much of a life outside his job at the SavMart, a Wal-Mart-style monstrosity bathed in bleak fluorescent light and buzzing with aisle after aisle of hypnotic sameness.
His putty-colored uniform matches his skin, matches his hair, matches his apartment, we learn when he goes home at night. It's the ideal manifestation of his personality: inoffensive, bland, forgettable.
Or is it? When Nina Yorkin (Connie Nielsen) comes in with a roll of film from the birthday party of her son, Jake (Dylan Smith), Sy comments on how lovely her family is, what a good time they seem to have had. He should know, having developed their photos for years and watched Jake grow up on 4-by-6 color prints.
It seems at first that he observes Nina's pictures so acutely because he takes his job so seriously - to the point where he gets uppity about slight imperfections in the developing machine, prompting his pigheaded boss (Gary Cole) to remind him, "You need to take another look at your place on the food chain."
But there's a hint of something else in his voice. Love? Envy? And it surfaces again later when he sees Nina's husband, Will (Michael Vartan), at the store and comments, "You're a very lucky man, Mr. Yorkin."
Only later, when we see a collage of the Yorkins' photos that takes up an entire wall in Sy's apartment, do we understand how consuming his attachment is to them. The image is striking, but it doesn't tell the whole story.
The Yorkins are young and gorgeous and beautifully dressed, and they live in a modern, impeccably decorated home. But they're not perfect, and that revelation really sends Sy over the edge.
We've known since the beginning that he did something - the film begins with him being interrogated by a police detective, played by Eriq La Salle - we just don't know what that something is. Romanek subtly, skillfully builds tension toward a climax that's surprising - if a bit disappointing - but definitely different, and not what you'd expect.
"One Hour Photo," a Fox Searchlight Pictures release, is rated R for sexual content and language. Running time: 98 minutes. Three stars (out of four).