Detective Vance found a coded message left by a dying spy: '5, 9, 12, 15.' The spy pointed faintly to a bookshelf containing an encyclopedia set. Vance pulled the 5th book, but it was empty. He realized the spy was using a different cipher. What did the numbers actually represent?
Alphabetical order
Converting the numbers to letters using A=1, B=2 gives E (5), I (9), L (12), O (15), spelling the word 'EILO'—wait, 5=E, 9=I, 12=L, 15=O spells EILO, which spells 'OIL' or 'ELIO' or refers to the 5th, 9th, 12th, and 15th letters of the alphabet.
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: Medium. More like this: Detective riddles with answers or try Truth & Lie Island for a different kind of puzzle.
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