This is a Young Adult novel about one of the Batman's Greatest cases. Well, Greatest according to our young narrator, who admits he's a bit biased because he gets to help.
The story is pretty staight ahead actioner. Recently moved to Gotham City from East Texas, our your narrator decides to creep onto a rooftop to help a cat -- it's just the right thing to do. There, he stumbles onto a mystery. The Joker, Clown Prince of Crime, has himself an airship and he's up to no good! It's up to our hero (with a little help from Batman, all right a bunch of help) to figure out the sinister plot and put an end to it.
Fun, fun, fun. This novel reads like a great comic book, the kind of thing you just don't want to put down. Luckily, the size is such that you'll be done in an hour or two. Makes great reading aloud, too.