The Clockwork Ghost

After their home is destroyed while pursuing a century-old cipher, Tess, Theo, and Jaime keep following the trail left by the Morningstarrs. The clues lead them through an alternate, steampunk-tinged New York where hidden technology, secret architecture, and strange allies and enemies complicate every step.

As the mystery deepens, the trio is forced to split time between new living arrangements and their shared mission, all while solving increasingly difficult puzzles. Their search brings in unexpected perspectives, dangerous rivals, missing animals, and new discoveries that make the cipher feel bigger and less straightforward than before.

The investigation becomes more perilous as the kids realize they are not the only ones chasing the answer and that the city itself may be tied to the puzzle. The book builds toward a major cliffhanger, leaving many questions open and pushing the series toward its next installment.