Chasing Vermeer (by Blue Balliett)

As they track down clues, their investigations lead them in many directions: an old lady in the neighborhood, a famous bookstore, their teacher, a book of freakish phenomena, a friend's disappearance, and a series of odd coincidences. No one is what they seem to be, and Petra and Calder don't know whom they can trust.

Blue Balliett's first book is a thinking child's mystery, filled not only with the traditional accoutrements of adult mysteries (clues, red herrings, multiple suspects, plot twists, concluding explanations), but also with secret codes (which the reader has to decode to read the whole story), mathematical patterns, hidden drawings, art history, and references to the real books of Charles Fort, who wrote in the beginning of the 20th century about unexplained phenomena. The fun comes not from solving the mystery, but from watching CHASING VERMEER's main characters figure it out.

This book will be a challenge even for accomplished young readers -- the author and illustrator encourage poring over it carefully and pausing to think and experiment. If one stretches out the reading too much it's easy to lose track of the myriad details, necessitating rereading. An intellectual challenge wrapped up in a mystery novel -- bright children are going to love this.