A seemingly chance meeting at the junk, the sign read “costume” jewelry bin of Sadie's Variety Store on New York’s Upper West Side, and the two rings discovered there, brings together Brooke and Piper, thirteen-year-olds from very different economic worlds of Manhattan. Brooke, a student at Public School 444 and the daughter of two research scientists, lost her mother in a lab accident that remains a mystery a year after the tragedy. Piper attends the Laurels School, a private school on Park Avenue and has moved with her mother to a new luxury high-rise near Brooke's more modest apartment. She misses her father, who travels internationally for business but has not responded recently to frequent calls, texts or FaceTime requests. Both girls are puzzled and troubled by unanswered questions regarding the fate of each absent parent.

The two rings they now wear take them to the Egyptian galleries of the Metropolitan Museum of Art and the atrium that houses the Temple of Dendur. Using the power of the rings they enter, through the temple, a staircase to an underground passage that leads to a chamber of magic-like technology, deep beneath the reservoir in Central Park. There they meet the mysterious Ms. Thomas and Ms. Nikola who attempt to recruit them into a century-old sisterhood dedicated to aiding New Yorkers in peril. Not until they rise to the challenge of saving Piper's headmistress from death, by using the wonders of the chamber and the rings, are these two girls drawn into the cause.

 

Their friendship grows as each new and more dangerous challenge forces Brooke and Piper to discover unknown talents and tap into unused personal strengths while questioning why they were chosen from so many young New Yorkers.