Diary of a Wimpy Kid: Dog Days is a 2009 novel by Jeff Kinney. It is the fourth book in the Diary of a Wimpy Kid series. The book is about Greg Heffley, a middle schooler who keeps a journal about his life. In this installment, Greg would rather spend his summer playing video games, but his mom wants to create family memories. The book is known for its laugh-out-loud humor, and the movie has a sweet message about father-son bonding and honesty