Twins Tess and Theo live in an apartment that was designed by the legendary Morningstarr twins in the 1800's. The Morningstarrs were the architects for all kinds of technology that is still in use today. They also left behind the Old York Cipher - a series of clues and puzzles that will lead to a huge treasure for whomever can solve it. So far, no one has managed to do that, not even the Cipherist Society of which Tess and Theo's grandfather was a member before he developed memory problems. The people of the apartment building get word that it has been purchased by Darrell Slant, a billionaire real estate developer who will likely raze the building and put up something new and shiny. With only a month until they will all be evicted, Tess and Theo feel like their only hope is to solve the Cipher and use the treasure to save their beloved building and piece of history. With the help of their neighbor, Jaime Cruz, they start off on their crusade which proves to be more dangerous than they imagined.
I was so into the first chapter of this book with Ava taking on the murderous stalker but then she disappeared entirely from the story. From then on the book felt youngish to me. Where are the Morningstarrs? Where is Ava? Where are the badass people who created all these amazing creatures, puzzles, and technology over 200 years ago? If I hadn't had my expectations raised by the opening chapter and the gushing about how amazing the Morningstarrs were, I probably would be more forgiving of what the book actually was - a fine mystery with young sleuths. There were a couple of twists I didn't see coming but more that I did. Especially the person who proved to be untrustworthy even though they were blatantly told to TRUST NO ONE!!! Considering that Theo apparently reads as much as I do, he should've seen that one coming. I also have issues with the clues and ciphers themselves because I don't feel like we, as readers, have much chance of deciphering them. A couple of the clues rely on knowing about some of the Morningstarr inventions which we obviously can't know When I'm reading a mystery I want to have a shot at solving it myself. If the author uses clues or characters that are not available to the reader, that's cheating. So in the end, the book is okay for me, but not great.