In an alternate England of 1851, spirited fourteen-year-old Sophronia is enrolled in a finishing school where, she is surprised to learn, lessons include not only the fine arts of dance, dress, and etiquette, but also diversion, deceit, and espionage.

"It was 1798 when the Morningstarr twins arrived in New York with a vision for a magnificent city: towering skyscrapers, dazzling machines, and winding train lines, all running on technology no one had ever seen before. Fifty-seven years later, the enigmatic architects disappeared, leaving behind for the people of New York the Old York Cipher -- a puzzle laid into the shining city they constructed, at the end of which was promised a treasure beyond...