Like "High Fidelity," About a Boy is based on a slight but effective novel by Nick Hornby that captured the thirtysomething male ethos with surprising accuracy. Unlike "High Fidelity," "About a Boy" stars Hugh Grant and winds up indulging in insultingly manipulative sentimentality. Superficial Will (Grant) lives a spoiled life thanks to royalty checks from a Christmas song his father wrote years ago. Hoping to meet women interested in meaningless sex, childless Will pretends to be a father at a support group for single parents. Instead, he finds himself teaching an unpopular child, Marcus (Nicholas Hoult), how to blend in at school--against the wishes of Marcus' suicidal mother, Fiona (Toni Collette). Credit "American Pie" directors Chris and Paul Weitz with trying something different and managing a few charming moments. Debit them for failing to develop their female characters as well as they do Will and Marcus; fully formed in the novel, Fiona here seems a skeleton of a woman, her passions for vegetarianism and social justice smugly mocked and simplistically linked to her depression.