I heard about this puzzle today and thought it might interest people here. Does anyone know of other famously difficult puzzles? Post them in the comments below. 
“Literary puzzle solved for just third time in almost 100 years”
One of the world’s most fiendish literary puzzles – a murder mystery in which all the pages are out of order – has been solved for just the third time in almost a century.
Cain’s Jawbone was dreamed up by the Observer’s first cryptic crossword inventor, Edward Powys Mathers, who was known as Torquemada. First published in 1934, it invites the reader to reorder the book’s 100 pages – the number of possible combinations is a figure with 158 digits – and solve the murders within.
“The pages have been printed in an entirely haphazard and incorrect order, a fact which reflects little credit on somebody,” wrote Powys Mathers at the time. “The author assures his readers, however, that while it is now too late for him to remedy the ordering of the pages, it is quite possible for them, should they care to take the trouble, to re-order them correctly for themselves.”