Dragon of Seas — P.C. Baccalario

In the fourth installment of the Century Quartet, Italian author P. D. Baccalario concludes the mystery that took four cities and four extraordinary kids to solve.

SHANGHAI, SEPTEMBER 19
As the equinox approaches, Sheng, Elettra, Harvey, and Mistral know they must come together one last time. Armed with only a map and a top that seem to be broken, a collection of old coins, and a tile with four knives painted on it, the four kids meet in Shanghai to try to make sense of clues that their predecessors couldn't decipher. Meanwhile Sheng is haunted by a dream and by visions of a young boy who seems to understand their quest. The visions send the kids all over Shanghai, through abandoned water ducts and ancient tea houses, in search of the Pearl of the Sea Dragon, an ancient stone that they're sure is the last piece of the puzzle. But a germophobic supercriminal who never leaves his sterile Shanghai skyscraper will do anything to learn their secrets....

Fans of Blue Balliet, Trenton Lee Stewart, and Michael Scott will be drawn to this Da Vinci Code-like adventure for kids.