Diary of a Wimpy Kid: The Last Straw is a novel by Jeff Kinney, the third book in the Diary of a Wimpy Kid series. The book is a journal that follows the adventures of Greg Heffley, the narrator, during the second half of his seventh-grade year. In the book, Greg battles his father's efforts to change him by getting him involved in organized sports and other “manly” pursuits. When Greg's dad threatens to send him to military school, Greg realizes he has to shape up