Balliett’s third mystery falls short of Chasing Vermeer’s brilliance, and the triangular friendship among Calder, Petra and Tommy, skillfully developed in The Wright 3, receives bumpier treatment here (2004; 2006). The three seventh graders experience a transformative field trip to view Alexander Calder’s massive, colorful mobiles. The scene shifts radically when Calder’s father takes his son along on a business trip to England. Calder goes missing and stays thus for nearly half the novel. Improbably, Petra, Tommy and their elderly friend Mrs. Sharp fly to England to assist. Intricate plotting involves Blenheim Palace’s maze, an anonymously (and roundly disliked) donated Calder sculpture stolen from Woodstock’s village square, a mysterious American named Art Wish, the influence of the elusive British guerilla artist Banksy, a gad-about cat and much more. Tommy and Petra’s pairing kindles mutual admiration but oddly hapless explorations—Calder, trapped in a Palace waterfall’s hidden crevasse, ends up rescued by cops. While a fourth adventure’s intimated, problematic construction and too many tidy dei ex machinis (including their nasty teacher’s turning terrific) mar this one. (author’s notes) (Fiction. 9-12)