Greg Heffley, a middle schooler, continues to document his life in his diary, this time focusing on his tumultuous relationship with his older brother, Rodrick. Greg navigates the ups and downs of adolescence, from dealing with embarrassing family situations to trying to fit in at school. As Greg tries to impress his crush, Holly Hills, and avoid the school bully, he also finds himself tangled in Rodrick's schemes and antics. Despite their constant bickering, Greg and Rodrick learn to appreciate each other's quirks and bond over their shared experiences, ultimately realizing the importance of family and friendship.