The Hound of the Baskervilles
Arthur Conan Doyle's Holmes on Dartmoor, and a legend with teeth.
173 cryptograms drawn from it, every one by Arthur Conan Doyle.
How hard they are
41 easy, 77 medium and 55 hard, graded by the model described in our guide to solving cryptograms.
They average 71.7 letters over 19.3 distinct ones, with 4.1 letters appearing exactly once.