The two brothers Grimm (Ledger and Damon) travel around the Napoleonic countryside vanquishing fake monsters and demons in exchange for cash. When the French government figures out what they're up to, they force the brothers to deal with the real thing a number of murders being committed under mysterious circumstances in the northern woods between Germany and France. It is there that they have to try and discover what's really happening and deal with it before more people are killed or their lack of success leads to the guillotine.