IT WAS WEDNESDAY EVENING, a.k.a. trash night. Steve Brixton, seventh grader, formerly of the Brixton Brothers Detective Agency, plodded along his driveway, dragging a maroon bin behind him. The bin’s wheels rumbled and popped as they rolled over pebbles on the blacktop. This week the Brixton family’s bin was very full. The lid would not close tightly; it bounced up and down, making an irregular, slow clapping sound. And the trash was heavy—Steve could feel the can’s weight in his elbow, and he kept switching the arm he used to drag it: right, then left, and back again. He sighed....