With his sad, expressive face seemingly fed by an inner wellspring of emotion and wisdom beyond his years, 20-year-old Kieran Culkin is shaping up to be one of the finer true actors of his generation — his only serious competition is Jake Gyllenhaal. But even Culkin’s intensely mordant performance here can’t make this pointless and brutal film watchable. Scion of old money, Igby Slocumb (Culkin: The Dangerous Lives of Altar Boys) exists in the center of a maelstrom of indiscriminate hatred and disregard: his mother (Susan Sarandon: Cats & Dogs, uncharacteristically shrill and phony) despises him, his brother (Ryan Phillippe: Gosford Park) wants nothing to do with him, and his father (Bill Pullman: The Virginian) has removed himself from the world, refusing his medication to wallow in severe schizophrenia. Pullman is stunning in his few brief appearances, and Culkin is extraordinary in Igby’s adolescent anguish, but it couldn’t have been hard to pretend you want out of this world. Even when Igby escapes from military school and goes on the lam, he continues to find himself surrounded by “friends” who turn suddenly and inexplicably violent or who suddenly and inexplicably betray his friendship. As an exploration of a flawed kid who brings interpersonal disaster upon himself, this would-be black comedy could have worked — but the fault lies not with Igby, a sweet and perfectly normally confused kid looking for his own identity, but with Igby’s creator, writer/director Burr Steers. Steers may be the god of his world, free to inflict unreasoning and senseless cruelty on his characters, but we don’t have to watch it.