Citizens of Saddleboro are proud to say that theirs is the cleanest town around. So they can't ignore the mysterious death of their mascot, Cock Robin. Some people would like to blame the citizens themselves, but one boy-Tony Isidoro -- suspects there's more to the story.

Tony threads his way through a maze of clues: Among other things, the town park is overrun with trillions of ants; nights are quiet because there are no frogs singing; the nearby river contains a dangerous amount of an unknown chemical; and the town dump is emitting strange fumes. What does it all add UP to? It's an eco mystery all right, and it's up to Tony to figure out who really killed Cock Robin.