The Twyford Code, by Janice Hallett

An old phone has turned up in a missing persons case containing 200 deleted audio files that may offer a clue. Ex con Steve Smith has recorded details of his bid to unravel a supposed secret code hidden in a series of mid-20th century children’s books that will unlock a mystery from his childhood. He has enlisted the help of his fellow former remedial English students to find out what happened to their missing teacher, Alice Isles, 40 years ago. But they all have conflicting memories of that fateful excursion and possibly, conflicting agendas. Their story unfolds through transcripts of the audio files and it is a twisted tale indeed, with the boundaries between truth and fiction constantly crossed and blurred. A deprived childhood, London criminal gangs, WWII spy drama, missing gold that may be cursed and an estranged son. What actually happened? Who is real? What is allegory and what is entertainment? There are a few too many convenient coincidences, but this is nevertheless a gripping read that keeps the reader guessing right to the end.