Chasing Vermeer by Blue Balliett
Mixture of mystery, puzzles, possibilities, and art. Brainy 12-year-olds Petra Andalee and Calder Pillay attend the University of Chicago Laboratory School where their teacher's unorthodox methods make learning an adventure. When Vermeer's A Lady Writing disappears on its way to exhibition at the Art Institute of Chicago, the two overcome their adolescent awkwardness and let their friendship bloom, pooling their talents to rescue the masterpiece and expose the thief. Many elements play a role in unraveling the secrets surrounding the crime: Calder's set of pentominoes; his encoded correspondence with his friend Tommy about a missing boy named Frog; and Petra's intuitive communing with the woman in the painting, all augmented by the unusual ideas presented in a strange old book that Petra has found.

Great fun!