We start with the Voynich manuscript, a whole book, probably from the fifteenth or sixteenth century in cipher form - though as Bauer points out, some believe it's a meaningless hoax. After a dabble with ancient ciphers, we next discover that Elgar was a cipher fan. I'd heard about his playful concealment in the Enigma Variations, but wasn't aware of the Dorabella cipher, which remains unsolved to this day. (Bauer also takes us through Elgar's own workings to solve a public cipher challenge, which is fascinating.) Then we zoom forward to the infamous Zodiac killings and their associated ciphers (the inspiration of the Dirty Harry movie), plus a number of other true crime stories with an unsolved cipher involved.
I was a bit wary about this section, as I'm no fan of true crime, but the cipher element made the whole thing much more of an intriguing mystery, where the details of the crimes were necessary for cipher's context. We then go on to a whole host of other ciphers, from attempts to use them to prove communication from beyond the grave to a whole world of 'challenge ciphers' I wasn't aware of. Here, the public is challenged to deal with a cipher, some via convoluted communications such as the enigmatic Cicada 3301 challenges which spanned websites and physical locations. And, of course, there is the CIA's famous Kryptos sculpture, still partially unsolved.
The book does have some minor irritations. Bauer can't resist exclamation marks - it's not just in the title, but almost every page seems to have them. (I can't help but wonder if there's a cipher involved, there are so many.) He also does tend to give us just a bit too much detail in the background information. So, for example, when tracing the early years of the Voynich manuscript, we are told too much dull detail, transcribing letters about it that don't add much to the narrative.
There's also an inherent difficulty in the topic, in that most of the ciphers covered are still unsolved, as the title suggests. This means that many of the stories in the book don't have an ending - or rather they all have the same ending 'We don't know yet...' which gets wearing after a while. It's fine that some of these can be seen as challenges for the reader, if so inclined - but it makes the book work a little less well. Many of the best bits of Unsolved! were where at least a partial solution was reached. The book might have worked better if Bauer had gone for more of a mix of solved and unsolved ciphers, so we could have had regular 'aha' moments during the journey.
Despite the many mysteries left hanging, though, this was a thoroughly engaging read. Whether you have the patience and fortitude to have a go at cracking ciphers yourself, or, like me, are happy to be impressed with the ingenuity but would never put the time and effort in, there are some cracking (sorry) stories and surprises here. What else can I say, but TIEL TKIA CEOB HSXL B!SN ENOC
Review by Brian Clegg