Wow! I loved this idea - it is terrifying to imagine being unable to recognise faces, especially your loved ones. Monroe really ramps up the paranoia - I couldn't guess where the text was going. I didn't have a clue for most of the book whether Kate's doppelganger theory was correct or whether it was all in her mind. Despite the book being relatively long, it was quick-paced and the tension never dropped. Often, the endings of thrillers can be disappointing, but I was very happy with this one. I'd never heard of ‘super recognisers’ before and am now keen to know if this sort of police unit really exists. I liked Kate as a character and her voice always felt pretty real to me. I also enjoyed the Jake and Silas chapters - all three protagonists were appealing and well-developed.