Actress and pop singer Hilary Duff brings her perky, vacuous persona to another plastic comedy, molded to delight younger teen and preteen girls from, say, ages 8 to 15 and to offend absolutely no one. The movie contains mild sexual innuendo and a theme about facing life after a loss.

"A Cinderella Story" casts Duff as a brainy high school senior. In an update of the classic fairy tale, she plays Sam Montgomery, who longs to attend Princeton but lives in a kind of indentured servitude to her nasty, Botox-bloated stepmom (Jennifer Coolidge, the film's best creation), who keeps Sam waitressing at the diner she inherited from Sam's beloved father. (His death in an earthquake is explained by Sam in the prologue.) Her stepsisters (Andrea Avery and Madeline Zima) are idiotic (and unfunny) tormentors. How Sam roles her perfectly mascara'd eyes and suffers! She drives a classic Mustang convertible, has an anonymous e-mail romance with a boy (Chad Michael Murray) from school whom she doesn't know she knows, and gets moral support from her pals Carter (Dan Byrd), a wannabe actor, and Rhonda (Regina King), a fellow waitress. We're betting Sam will triumph.

I, ROBOT (PG-13, 114 minutes)

Often stunning in its visualization of the near future, where polite, talking robots work for humans in all aspects of life, "I, Robot" disappoints somewhat as a hybrid action flick/sci-fi thriller. Even star Will Smith's cynical cop seems to be in the wrong film at times. His smart cracks fall flat amid the shiny, computer-generated robots and other effects. Yet teenagers may overlook the movie's awkward shifts in tone and enjoy Smith's presence, the gadgetry and the impressive chase and fight scenes between him and a line of mysteriously aggressive robots. The film includes low-grade profanity, a hint of nudity, fights, bloodless gunplay, humans tossed about, robots crushed, a man's prosthetic arm damaged, a suicide theme and drinking.

Based in part on stories by Isaac Asimov, the movie opens in Chicago circa 2035 as homicide detective Del Spooner (Smith) investigates the death of a scientist (James Cromwell) who falls from a window at a robotics company, just as they're about to put a new line of 'bots on the market. Spooner, a robot-hater, suspects a robot pushed the man. The CEO (Bruce Greenwood) is offended at the implication that a robot would do harm, but a prim company psychologist (Bridget Moynahan) works with Spooner to find the menacing truth. A robot named Sonny (generated from actor Alan Tudyk's movements), programmed with human emotions, could hold the answer.

THE DOOR IN THE FLOOR (R, 111 minutes)

Rich in atmosphere and thick with banked emotion, this beautifully realized tale of love, sex and family heartbreak aims its dramatic riches at audiences 17 and older, and not just because of its explicit sexual situations and nudity. The slow, deliberate way it reveals the inner lives of its characters makes it a better choice for college kids with a few more art films under their belts. The graphic sexual situations involve an older woman and a 16-year-old boy and include nudity. Other scenes imply masturbation. Some characters drink heavily and use profanity.

Writer-director Tod Williams adapted "The Door in the Floor" from the first part of John Irving's novel "A Widow for One Year." Jeff Bridges plays Ted Cole, a successful children's book author and would-be artist. He hires Eddie (Jon Foster), a prep school teenager, as his assistant for the summer at the Coles' home in the chic Hamptons. While the caddish Ted has a fling with a neighbor (Mimi Rogers), young Eddie grows besotted with desire for Ted's sad and lovely wife, Marion (Kim Basinger). Paralyzed with grief over the deaths of their two sons in a car wreck a couple of years before, she ignores their needy 4-year-old daughter (Elle Fanning), yet Eddie's awkward desire arouses Marion. Their affair reopens the family's wounds.