When his cat Jerome brings him a fragment of his sister's diary, Marty decides that the cut off phrase "My brother is we..." must mean that he is a werewolf! He makes a list of 12 different qualities that might manifest themselves if he is, and throughout the book, more and more seem to pertain to him. His friends Parker and Roongrat try to help him, but Marty wants to make sure that they are safe as well. In the meantime, he has to deal with is sister, who is preparing for a quiz bowl type tournament, neighborhood bully Peach Fuzz, and a trip to the town dump to try to retrieve the diary. Luckily, Marty's love for candy has given him a cavity, which manages to cure his condition.
Like the first Marty Pants, this has a lot of goofy, improbably events accompanied with comic illustrations. There's a little more plot the the majority of Wimpy Kid books, although there are lots of humorous, unrelated anecdotes as well. Marty is clearly not the brightest bulb, and young readers will enjoy knowing more than he knows.
Readers who enjoy James Patterson's or Michael Fry's notebook novels, or are big fans of Watson's Stick Dog or Moore's King of the Bench books will find the mixture of funny text and illustrations to be just right.