A witch's treasure room has three doors labeled Alpha, Beta, and Gamma. A scroll states: 'Only ONE of the three witch guards tells the truth.' Witch Red says: 'The key is behind Door Beta.' Witch Blue says: 'Witch Red is lying.' Witch Green says: 'The key is NOT behind Door Alpha.' Behind which door is the key located?
Door Alpha.
If the key is behind Door Alpha, Red lies (key isn't in Beta), Green lies (claims key isn't in Alpha), and Blue tells the truth (stating Red lies). This satisfies the condition that exactly ONE witch tells the truth.
About this riddle
Detective riddles are tiny mysteries. Look for the detail in the story that does not fit; it is usually the clue that solves the case.
Difficulty: Hard. More like this: Detective riddles with answers or try Truth & Lie Island for a different kind of puzzle.
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