Case 45 · wordplay / sets · Medium · About 7–10 minutes
An observatory clerk keeps three registers for every delivery. Two registers record possible letters; the third lists letters that must be rejected. The surviving characters identify one direction.
There are five deliveries, and their row order is fixed. You need no compass, star knowledge, or interpretation of the accompanying art.
For each row, find the letters occurring in both A and B. Then discard any of those letters that also occurs in C. Exactly one distinct letter will remain in each row.
| Row | A | B | C |
|---|---|---|---|
| 1 | LANTERN | NOODLE | LEAF |
| 2 | COPPER | ORCHID | CRISP |
| 3 | RAVEN | BRIAR | CABIN |
| 4 | THIMBLE | STONE | HONEY |
| 5 | SHADOW | HEARTH | WART |
Read the five survivors from row 1 to row 5. What direction is recorded?
Repeated occurrences do not matter. Treat a letter as either present or absent in each word. You are not subtracting letter counts, matching positions, finding anagrams, or choosing a shared sound. All strings use their exact printed uppercase spellings.
For a separate miniature example, if A were ABC, B were BCD, and C were B, the common letters would be B and C; rejecting B would leave C. That example is not an extra message row.
Hint 1 - reveal when you want a nudge
Make the shared-letter list before consulting C. A letter found only in A cannot survive, even if it is absent from C.
Hint 2 - reveal when you want a nudge
In row 1, LANTERN and NOODLE share L, E, and N. LEAF removes L and E, leaving N.
Reveal the solution and explanation
The direction is NORTH.
- Row 1: the common letters are L, E, N. C removes L and E, leaving N.
- Row 2: the common letters are C, O, R. CRISP removes C and R, leaving O.
- Row 3: the common letters are A and R. CABIN removes A, leaving R.
- Row 4: the common letters are T and E. HONEY removes E, leaving T.
- Row 5: the common letters are H and A. WART removes A, leaving H.
Each row therefore has one survivor before the five letters are combined. The recognizable direction confirms the extraction but is not needed to choose among multiple surviving letters.
A complete check tests every alphabet letter for three conditions: present in A, present in B, and absent from C. Applying that test independently to all five rows gives the singleton sets N, O, R, T, H. Extra occurrences such as the repeated O in NOODLE or R in BRIAR do not change membership. Reading the rows backward would contradict the stated order and is not an alternative solution.
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