In the time when caveman are hunters and woman are gatherers. We are introduced to an incompetent hunter Zed (Jack Black) and a virgin boy gatherer Oh (Michael Cera) who are unable to carry out their tribal duties or obtain the affection they desire from a few less than interested cave woman. As the outcasts of the tribe Zed convinces Oh there must be more to life than the village they live in. They trek to the Tree of Knowledge.  Zed decides to break the rules and eat the fruit in order to increase his intelligence. However the village decides to exile them for doing this and they are forced to journey into the land unknown.

The movie continues to keep with certain elements from the Bible as their adventure introduces them to Adam, Cain and Abel (well for a minute before Cain kills him), from town to town, Sodam to Gomorrah, not to mention meeting a Princess and a High Priest that takes Oh as his personal slave to baste his body in oil. Its comedy stretched as far back as the time its set in and will either have you laughing for 95 minutes or wishing you read the telephone directory instead.