Cain's Jawbone is a murder mystery puzzle written by Edward Powys Mathers under the pseudonym "Torquemada".
When the book came into the public domain, crowd-sourcing publisher Unbound resurrected the original contest to solve Mathers' puzzle.
There is no longer a contest or prizes but if you think you have solved the novel's mysteries, I have created a facsimile of the contest submission form so you may instantly verify your puzzle-solving skills. Check your answers here.
Whether or not you succeed in solving the Cain's Jawbone puzzle, check out the definitive guide that lays it all bare for you and questions the authority of a single solution.
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