You are in the intersection of two roads, there is a troll in the beginning of each road.
One of them is liar (always lies), and one of them always tells the truth.
One of the roads, ends to your destination and one of them ends to death :) .
The trolls know which way is the right one and which one ends to death.
How can you find the way if you can ask only one question?
it's your choice who to ask from and you don't know who tells the truth and who lies.