A mystery novel for 6th graders. The first of a set of 3 separate “mystery” books in the “Hardy Boys / Nancy Drew“ genre. Two children, Calder and Petra, are neighbors and classmates at a school located on the University of Chicago's Hyde Park campus. When a famous painting by Johannes Vermeer, called “The Lady Writing” gets stolen while it is being transported to the Art museum in Chicago, they follow various clues to trace the missing painting.

The book is very nicely written for its intended audience and has a couple of novelties: first, Calder and his friend, Tommy, exchange messages using a substitution code throughout the book. The book gives the code in a tabular form and the messages in coded form. The young readers are expected to work through the substitution each time to see what the two friends are writing to each other in code. Second, throughout the book are nice illustration in which visual clues are displayed. The readers are expected to identify and then work with the clues to decode the special message of the book (solution at scholastic.com). So the book maintains interactiveness with its audience in a sustained fashion.

Calder and Tommy are also ardent fans of the “Pentominoes”. As the book explains, “A set of pentominoes is a mathematical tool consisting of twelve pieces. Each piece is made up of five squares that share at least one side. Pentominoes are used by mathematicians around the world to explore ideas about geoemtry and numbers” (followed by the diagrams of the pentominoes).

Playing with combinations of pentominoes to create rectangles of various sizes spurs Calder to try combinations of words (When his Art teacher, Ms. Hussey, tells the class about Picasso's quote, “Art is a lie which tells a truth”, he wonders if he can come up with something similarly simple and deep by combining “art”, “lie” and “truth” in other ways. From there, he muses: "Maybe all of life was about rearranging a few simple ideas. If he could just get to those simple ideas, with a little practice, he'd be a cross between Einstein and that mathematician, Ramanujan — or maybe Ben Franklin."

When they try to teach an elderly neighbor, Mrs. Sharpe, about Pentominoes, she is unable to form rectangles and in frustration, asks them a combinatorial problem unwittingly, “How many, oh, five-letter words, say, could you make using at least three of these twelve letters in each word?”