Feeling unappreciated, Humphrey the beaver wants to do is build his Grand Dam. However, his efforts are ignored by the community of woodland creatures around him. Everything changes when a billboard from the city becomes lodged in his dam. The arrival of the object seems like divine intervention and makes Humphrey the new leader. But an over-ambitious the beaver goes too far when he gets the chance to realise his ultimate dream, endangering his friends, his home and eventually his own life.