A mystery adventure trilogy following twins Tess and Theo Tupper and their friend Jaime as they race to solve the Morningstarr cipher before their apartment building is demolished. Set in an alternate-history New York shaped by inventor siblings' advanced technology, the books blend puzzle-solving with steampunk elements, friendship, and ultimately revelations about the cipher's true purpose and the city itself.
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.