Arthur Conan Doyle Cryptogram — Free Online Puzzle
Decode verbatim sentences from two books by Arthur Conan Doyle.
How to play
Each printed cipher letter stands for one different answer letter. The same substitution is used throughout the sentence, and no letter stands for itself. Spaces, apostrophes and punctuation stay in place. Your task is to recover the exact sentence from the book. Short texts may admit other readings; we check against the original sentence, without promising a unique decryption.
Tap a guess box to select every occurrence of its cipher letter. Use the on-screen A to Z keyboard or type a letter on a physical keyboard. The guess appears above every matching cipher letter. Erase, Backspace or Delete clears that substitution. Left and right arrows move between different cipher letters. A red border means the same answer letter has been assigned to two different cipher letters.
Check compares your entered substitutions with the original and reports how many need another look. Hint fills one correct substitution everywhere that cipher letter occurs, even if you previously guessed it incorrectly. Undo restores the previous guesses. Reset restarts the same puzzle with your chosen starter setting. Normal begins with zero letters; Easy begins with two correct substitutions. These labels describe the starting help, not a measured difficulty.
The timer starts with your first entry or hint and stops when you solve or reveal the answer. Show solution reveals the full sentence with its title, author and first book publication year. Revealing does not earn a daily solve, even if you reset and fill the answer afterward. Solving with letter hints still counts. Share is available after a solve and contains your time and puzzle link, never the sentence.
A short history
Substitution ciphers disguise a message by replacing its letters. In a simple substitution, one replacement alphabet is used throughout. Word divisions turn this into a familiar pencil-and-paper puzzle. The American Cryptogram Association records a cryptography feature in Detective Fiction Weekly during the 1920s, and a local newspaper column called Secret Corner in Burton, Ohio. Its early members concentrated on simple substitution puzzles. Newspaper cryptograms retain word spacing so that readers can combine spelling patterns with letter frequencies. Read the association’s history. Read the cipher tutorial.
The daily puzzle is shared by UTC date and changes at midnight UTC. Author pages follow a fixed numbered sequence drawn from two books per author; New puzzle advances the sequence in your browser while the published starting puzzle stays fixed. Code chooses a verbatim sentence, makes a seeded substitution alphabet and checks guesses. All source books were first published before 1929. The text and its individual attribution stay hidden until you solve or choose Show solution. Progress and your daily streak are saved on this device.
Solving tips
Look for single-letter words: in ordinary English sentences they are A or I. Try common short words such as THE, AND, TO, OF, IN and IS, and compare their repeated-letter patterns with the cipher. A proposed answer must work at every occurrence of its letters, not just in one word. Remember that our substitution key never maps a letter to itself.
Apostrophes give useful clues without removing the need to check the whole sentence. A final apostrophe plus one letter might mark a possessive or a contraction such as IT'S. Longer patterns can suggest DON'T, CAN'T or WOULDN'T. Double letters and common endings such as ING and ED can connect several words at once. Test a possibility, then use Undo if the other words stop making sense.
Letter frequency is a starting point, not proof. E and T are common in English, but a single short sentence can have an unusual mix. Read the emerging words together, use punctuation to find clause boundaries, and compare several possible substitutions. A hint reveals one correct answer letter wherever it occurs; Check can help you spot a mistaken assumption without showing the whole answer.
A daily streak counts consecutive UTC dates solved, including solves with hints or the Easy starter. Replaying a date does not add another day. A revealed puzzle earns no solve. Your dated daily link keeps that day's puzzle available after midnight, and an author puzzle link includes its sequence number. There is no countdown, account requirement or time limit.
Authors and books
This sequence draws from the two books below. The list describes the pool; the current sentence’s source is revealed with the solution.
- The Adventures of Sherlock Holmes · Arthur Conan Doyle · 1892
- The Hound of the Baskervilles · Arthur Conan Doyle · 1902