Thank you HarperAudio Children’s, HarperCollins, and NetGalley for the advanced electronic audio review copy of this book. This is a continuation of Rayleigh Mann’s adventures and in this book he and his friends are on an exciting treasure hunt through the Below-London to unravel a mystery and prevent chaos that is about to befall Below-London. I really enjoyed the audiobook version. Great narration, fast moving plot, awesome world-building, and the familiar characters combine into a wonderful story that I just devoured in one sitting. If you enjoyed Aru Shah and/or Amari and the Night Brothers, this book is for you! Looking forward to the next installment!