In this third installment of Blue Balliet’s art mysteries, everything is hanging by a thread. Focusing on the artwork of Alexander Calder, particularly on his mobiles and stabiles, the mystery deals with the disappearance of two Calders—the protagonist Calder Pillay, and an Alexander Calder sculpture. Calder Pillay, a twelve-year-old from Chicago, is on a business trip with his father in a small town near Oxford. When he goes missing, his good friends Petra and Tommy fly to England to search for clues. But while Petra and Tommy are both friends of Calder’s, their relationship with one another is prickly. Certain that their expertise with words and symbols will aid them in finding their friend, it isn’t until they join forces that they start to make real progress, cementing their own friendship in the process. Like a Calder mobile, the pieces and players in Balliet’s story are in constant motion. Petra and Tommy become desperate to understand the message of the British graffiti artist Banksy, the motives of certain town residents, and the twists and turns in an old hedge maze. Also embedded in a story certain to inspire thinking and conversation about art—what it is, how it is or is not valued—are clever clue-containing illustrations by Brett Helquist. (Ages 8–12)