Due to his grandmother's loving (if misguided) influence, Huge is fascinated with noir detectives and fancies himself to be a developing Sam Spade. Anchored to this self-image and further weighed down by his own obsessive nature, Huge is set out on a self-destructive investigate of some incidental vandalism - his first 'real case'.
The mystery elements are entertaining (and, I have to admit, I was shocked by the culprit), but the real story is Huge's coming of age.
As he pedals around town in his last year before junior high, Huge slowly but steadily learns what the difference is between a boy (even a boy detective) and an adult, with all the weighty responsibility and acceptance of human frailty the latter entails. With less-than-subtle references to The Catcher in the Rye, Walden and the Raymond Chandler books, the author is clearly out to describe life for a modern outsider - and he succeeds. Huge is alienated from the world around him in a wide variety of ways (many of them self-created).