The book reviews of UK children's author, Brian Keaney
                  
                                    
                                       Harris' novel about a spy in wartime Bletchley Park is one of his earliest and most successful thrillers. It's a thoroughly well-turned piece, meticulously researched with strong characterisation and a gripping plot. 
The structural-engineering is perhaps a shade more obvious than I would have liked and it leans a little heavily on the tropes of the genre. (I think he's become a better, and a more serious writer with time.) Nevertheless, it's a compelling and entertaining read with some satisfying plot twists and a confident narrative voice.