Mandie and the New York Secret

is the thirty-sixth book in the Mandie series.
==Book Description==
Mandie, Joe, and Celia arrive in New York, eager to see their friend Jonathan and learn the secret he has discovered. But they no sooner arrive than find out Jonathan has gone off to Long Island! Wild with curiosity, Mandie isn't sure she can wait for his return. Surely there's a clue somewhere....
(Description from Mandie.com)