Puzzle - find the safe path

From www.ft.com

Two guardians watch over a fork in the road. One path leads to safety, the other to a grisly death. One of the guardian is a knight, meaning that he always tells the truth. The other is a knave, meaning that he always lies, answering “yes” to questions whose correct answer is “no”, and vice versa. You do not know which guardian is a knight and which is a knave. With a single question, how will you find the safe path?


Order books