This Is Not My Hat is a companion piece to Jon Klassen's earlier I Want My Hat Back, only it takes place underwater instead of in a forest; and the story is told from the point of view of the thief and not the, er, victim. The end result, however, is pretty much the same. If you don't like I Want My Hat Back because of the conclusion, you will not like This Is Not My Hat, either. It helps to have a sense of humor. It helps even more if your humor has dark tendencies.
The artwork for This is Not My Hat is every bit as wickedly delightful as the earlier book's, with a bit more of a build-up in the tension and a seek-and-find on one of the two-page spreads.