"Every hundred years, four kids from four cities must save the world."
Rome, December 29.
A mix-up with their reservations forces Harvey from New York, Mistral from Paris, and Sheng from Shanghai to share a room with the hotel owner's daughter, Elettra. The four kids discover an amazing coincidence--they all have birthdays on February 29, Leap Day. That night, a strange man gives them a briefcase and asks them to take care of it until he returns. Soon afterward, the man is murdered.
The kids open the briefcase. In it they find a series of clues that take them all over Rome, through dusty libraries and dark catacombs, in search of the elusive Ring of Fire, an ancient object so powerful that legend says even a Roman emperor couldn't control it.
In the first book of the Century quartet, Italian author P. D. Baccalario begins a mystery that will take four cities and four extraordinary kids to solve.

"From the Hardcover edition."

In the second installment of the Century Quartet, Italian author P. D. Baccalario continues the mystery that will take four cities and four extraordinary kids to solve.
NEW YORK CITY, MARCH 15
Another mysterious artifact reunites Harvey from New York, Elettra from Rome, Mistral from Paris, and Sheng from Shanghai. Soon they discover a series of four postcards written in code years ago by the murdered professor who sent them on their quest in Rome. The cards send the kids all over New York City, through old libraries and abandoned tunnels, in search of the Star of Stone, an ancient object fundamentally connected to the earth. But a new set of villains, predators of Manhattan nightlife, will do anything to stop them . . .
Fans of Blue Balliet, Trenton Lee Stewart, and Michael Scott will be drawn to this "Da Vinci Code"-like adventure for kids.