Frankenstein
Mary Shelley's modern Prometheus, in letters and confessions.
205 cryptograms drawn from it, every one by Mary Wollstonecraft Shelley.
How hard they are
63 easy, 95 medium and 47 hard, graded by the model described in our guide to solving cryptograms.
They average 76.2 letters over 19.5 distinct ones, with 3.8 letters appearing exactly once.