Mister Max: The Book of Lost Things
When 12-year-old Max's actor parents leave for unknown parts without taking him, he is forced to survive by his wits. His grandmother lives next door, but he rather likes the independent life, and so, to support himself, he becomes a "solutioneer": helping people with their problems in creative ways, and sometimes incorporating costumes and roles from his parents' theater company. He solves several little puzzles in creative ways. A marvelously satisfying read.