Ummmm… when no one wants to come to Caterpillars party he makes new friends. Its new friends are different parts of itself.  It has a grand time, but a nightmare makes it worry about all of them leaving him, and then it takes a bath.  That is where the story ends, but this bath would make the friends leave since they were just drawn on to begin with.  This is actually a really sad book wrapped up to be a comedy.