Summer in Seattle...

One week before school lets out for the summer, 7th graders Wilbur and Tess take a trip to the local zoo. Once there, Tess meets Marcus, a cute, inquisitive boy who just moved to Seattle from Australia. Meanwhile, Wilbur meets a punk-rock zookeeper named Sarah, who allows Wilbur to feed some bats. That very day, Wilbur witnesses something terrible he can't forget; something he wasn't supposed to see.

Wilbur convinces Tess to sign up as a volunteer at the zoo to help him solve the mystery. All the while, (much to Wilbur's dismay) Marcus befriends other kids Wilbur can't stand: a geeky science nerd named Doug Farber, the portly and strange Martin Schoebel, and, worst of all, the annoyingly perfect soccer star Dakota Tawning.

Struggling with these and other distractions, along with the awkwardness of being a 14-year old boy, can Wilbur stay focused long enough to solve the Mystery at the Zoo?