A naive and idealistic Midwestern insurance agent (Ed Helms) feels as though he’s been thrown to the wolves when he’s suddenly given the job of representing his agency at the regional convention. At the actual event, he finds himself sharing a room with the roistering Dean Ziegler (John C. Reilly), against whom he has been expressly warned, and Ronald Wilkes (Isiah Whitlock Jr.), who is apparently the first African-American ever to enter Tim’s personal space. And soon he’s also getting attention from another conventioneer, the feisty Joan Ostrowski-Fox (Anne Heche). Tim’s ribald fall from an improbable middle-American innocence is the main action in this festive comedy of an innocent abroad, and his spur-of-the moment carousing with Ziegler, Wilkes and Ostrowski-Fox represents an antic sort of coming-of-age. The populist spirit of Frank Capra may hover in the background at times, but Cedar Rapids has more invested in a middlebrow celebration of saving graces to be discovered from a mildly diluted cocktail of sex, drugs and rock ’n’ roll. Helms is a hilarious version of a contemporary Candide, and Reilly is in rambunctiously fine form. Pageant Theatre. Rated PG-13.