JACK AND ANNIE are on a mission to save Merlin from his sorrows! Charged with finding the second of four secrets of happiness, the brother-and-sister team travel back in the magic tree house to the period known as the Renaissance. This time, Jack and Annie will need more than a research book and a magic wand. They'll need help from one of the greatest minds of all time. What will they learn from Leonardo da Vinci? "From the Hardcover edition."Osborne, Mary Pope is the author of 'Monday With a Mad Genius ', published 2007 under ISBN 9780375937293 and ISBN 0375937293.