So you want to get to the castle?
Well, then, you'll have to answer the riddle.
With a little smile, Sarah said to Ralph, "Answer yes or no. Would he," and she pointed at Alph, "tell me that this door," she pointed at the door behind Ralph, "leads to the castle?"
Alph and Ralph looked at her, then at each other. They conferred in whispers.
Ralph looked up at her. "Uh . . . yes."
"Then the other door leads to the castle," Sarah concluded. "And this door leads to certain death."
"How do you know?" Ralph asked slowly. His voice was aggrieved. "He could be telling you the truth."
"Then you wouldnít be," Sarah replied. "So if you tell me he said yes, I know the answer was no." She was very pleased with herself.
Ralph and Alph looked dejected, feeling that they had obscurely been cheated. "But I could be telling the truth," Ralph objected.
"Then he would be lying," Sarah said, allowing herself a broad smile of pleasure. "So if you tell me that he said yes, the answer would still be no."
"Wait a minute," Ralph said. He frowned. "Is that right?"
"I donít know," replied Alph airily. "I wasnít listening."
"Itís right," Sarah told them. "I figured it out. I never could until now." She beamed. "I may be getting smarter."