If you've already mastered the Rubix Cube and you've tried every escape room in town, we may have your next puzzling obsession right here.
'Cain's Jaw Bone' is a complex literary puzzle that was originally published in 1934.
Back then, only two people are known to have successfully solved it, and the solution has never been revealed publicly.
Now UK-based Kiwi publisher John Mitchinson has brought it back, and it's been a surprise hit.
A new edition came out in Australia and New Zealand last month, and Harper Collins is offering a $1200 prize pack to the person who can crack the code.
John, the co-founder of Unbound Publishing speaks to Jesse.