Parents Frank and Susan Heffley tell their sons Greg and Rodrick that they need to spend more time together. Susan incentivizes them with "mom bucks", which they will earn for real money depending on the hours they get along together, as she is writing a parenting column in the local newspaper. When a local talent show is announced, Rodrick hopes it will be the big break for his band, Löded Diper. As a prank he later stains Greg's pants with chocolate at church, causing a scuffle and harming Susan's reputation. Susan, Frank, and the youngest brother, Manny go on a trip, leaving Greg and Rodrick home for the weekend to work on their bonding along with an instruction to not have any guests. Disobeying these orders, Rodrick throws a wild party by inviting his teenage friends over, in which Greg and his friend Rowley Jefferson participate, and Greg and Rodrick start to bond. The next morning, they receive a voicemail from Susan and Frank saying Manny is sick so they will be returning home early. In a panic, the brothers manage to clean up the house, but notice that graffiti in permanent marker has been put on the bathroom door; they switch the door for one from the basement, only to realize that it lacks a lock. Susan notices and confronts Greg, who claims Rodrick only had people over for band practice. He begs Susan not to punish Rodrick, suggesting it would ruin their improving relationship. Rodrick, believing Greg kept their secret, gives Greg advice on both school and girls. Later, photographic evidence of the party is discovered when Frank attempts to present a slideshow of his Civil War figurines to Susan's editors. Frank and Susan punish Greg and Rodrick by having them spend the weekend with their grandfather at his
retirement home and prohibit Rodrick from participating in the talent show. At the retirement home, Greg runs into his classmate and crush Holly Hills, who is visiting her grandmother. Like him, she is the middle child between a malicious older sibling and spoiled younger one and they become good friends. The family goes to see the talent show, where Rodrick finds he has been kicked out of his own band by Bill Walter, a guitarist he recently recruited, while Rowley's magic act is in jeopardy due to his assistant's stage fright. Greg strikes a deal with Susan that he will stand in as Rowley's assistant if she lets Rodrick perform. "The Remarkable Rowley" and "Greg The Great" are praised by the audience, including Holly, believing the act is a comedy skit with intentional mistakes. The audience is not as impressed by Löded Diper, until Susan starts dancing at the edge of the stage, prompting the crowd to join in. Frank secretly videos Susan dancing, while Rodrick kicks Bill out of the band and reconciles with Greg. Greg and Rowley upload the video of Löded Diper being upstaged by Susan's dancing to
YouTube. It goes viral, angering Rodrick. ==Cast==