Steven Smith, as a young boy in his remedial English class, gave his teacher a copy of a book he had found on the bus – a children’s book by Edith Twyford, a children’s author who had fallen from grace due to her outdated values. The book’s margins were full of strange markings and notes, but his teacher, Miss Iles became obsessed with it. Soon after, she took Steven and his four classmates on a trip to the author’s home – but Miss Iles never returned and Steven has no memory of the end of the trip…

Many years later, and Steven is out of prison after a long sentence. He becomes determined to finally discover the truth about Miss Iles’ fate. She had been convinced that there was a complex code woven throughout Twyford’s books, the so-called Twyford Code, and she was, apparently, not the only one who believes in the code’s existence. But where does the code lead? What treasures does it hide? And why are people apparently willing to kill to keep it a secret?

And the winner for the most difficult book to review without spoiling it goes to…

OK, so let’s take the set-up first of all. This one, Hallett’s second book following the brilliant The Appeal, is presented as a sequence of automated transcriptions of audio files found on the mobile phone that belonged to someone who has gone missing. They have been sent to a university professor for their opinion, but there is a bit of a catch, because as the audio files have been automatically transcribed, there are some mild errors in the text – “missiles” for example rather than “Miss Iles”.

As the transcripts go on – initially Steven’s audio diaries, both on the present, the events when “missiles” disappeared and his more recent past in the criminal fraternity, and then, once he works out how to record conversations, some… well, conversations – it becomes clear that perhaps there is more going on than the reader initially imagined.

That’s probably all I can say about the plot, so let me make one thing clear before I have a bit of a moan – this is an outstanding piece of work. I was carrying it around, couldn’t put it down. It absolutely gripped me from beginning to end, and while I twigged where it was going – more in a “I can’t believe that this is possible but…” way that a rational razor-sharp deduction, that didn’t stop me being impressed by it.

The problem is that it’s too clever, really. If the reader is going to crack the Twyford Code – and I’m sure that some readers would want to sit down and devour it a la Masquerade, for example – then it really needed a “Challenge To The Reader” or some such interruption or warning. Once we get to the final section, I felt there was a little bit of an information dump. I wonder – did the author initially want to keep the detail revealed in the finale quiet for the dedicated codebreaker to try and solve, because I think that would have worked. The finale still works if the detail is kept nebulous, I think, and we would have had a puzzle that people might have been speculating about for a good while. The puzzle is deeply impressive how it is all put together, but more time pondering it – for some readers at least – might have been appreciated.

Regardless, this is a great read, although I think putting “The Modern Agatha Christie” on the front of this one (as opposed to on the front of The Appeal) might leave some people confused, as this is far, far from Dame Agatha. Still damn clever though.