This middle-grade fantasy mystery series is set in an alternate version of New York City where technology developed along a different path and the city is full of hidden puzzles left behind by three inventors centuries earlier — and follows two children who discover they are the key to solving a mystery hidden throughout the city itself. The series is inventive, richly atmospheric, and celebrates curiosity, history, and the thrill of a puzzle that spans an entire city.
When twins Tess and Theo and their neighbor Jaime learn that their apartment building in an alternate-history New York is being torn down, they become obsessed with solving a centuries-old cipher left by the building's mysterious original architects—the Morningstarrs—whose advanced technology shaped the city. A richly detailed, endlessly inventive puzzle mystery. The first book of the York trilogy.
Tess, Theo, and Jaime follow the next layer of the Morningstarr cipher across New York City and into the secrets of the alternate-history past, discovering that the stakes of their treasure hunt are much higher than any of them imagined. A strong middle volume that deepens both the mystery and the characters' relationships.
The York trilogy concludes as the full scope of the Morningstarr cipher's purpose is finally revealed, and Tess, Theo, and Jaime must make a choice about what to do with what they have found. A satisfying and emotionally generous finale that honors the world and characters built across the trilogy.