The main character, named Tim Lippe (Ed Helms), is a rube, simple, naive, a boy in man's clothing. He has never left his home town of Brown Falls, Wisconsin, so when he is called on by the head of his insurance office to attend a convention in Cedar Rapids, which is a big town for this guy, he is so green he deosn't know that everyone, even him, has to go through security check, even when the security check guy is someone he knows very well.
Once in Cedar Rapids, the blowhard, played by John C. Reilly, the hip woman, played by Anne Heche, and the stolid roomate, played by Isaiah Whitlock, give our hero a little seasoning. Alia Shawcat, who played Maebe on Arrested Development, does a fine turn as a hooker. All the women, including Sigourney Weaver who bravely allows the camera to show her age, hold their own in this male id-centered comedy. The comedy comes and goes, but at heart, the film is a coming of age story for the sweet insurance salesman. It gives honest businessmen everywhere a reason to cheer.