Plot summary

The film opens with Grover Beindorf introducing himself: he is a kid who lives with his sister Stacey and his parents Ned and Janet in the suburbs of Ohio. Then follows a montage of videos taken over the Beindorfs 18-year-long marriage... which is an anniversary gift from Grover and Stacy. Unfortunately, Ned and Janet drop a bombshell on their children: they are considering a separation. A depressed Grover confides in his best friend Matt Finley, whose father Vic never keeps a wife for more than two years, who says if it was to him hed lock them in a closet until they sorted things out. This gives Grover an idea...That night, Grover and Stacy dress up the basement in a Hawaiian décor, inspired by their parents honeymoon in that country, and invite their parents down there for dinner in an attempt for reconciliation. Unfortunately, all Ned and Janet do are squabble with each other, so the kids leave them in the basement... and lock them in. They inform their flabbergasted parents that they will not let them out until they resolve their issues and go back to loving each other.The next morning, Grover informs Matt what hes done; however, the school bully TJ Krupp overhears them, and goes over to the Beindorf home to see for himself. He is impressed with Grovers feat, and decides to get involved: when Ned and Janet try to break out through the basement door, he installs a new, more secure one. Later, he throws into the basement his own parents, brash bullying Donald Krupp and his doormat wife Gwenna, so that THEY can level things between them. Matt too wants his father to keep his current wife Louise and locks them up too till they can manage to stay together.Later, Grover encounters Brooke Figler, a popular girl on whom hes had a long-term crush. She unexpectedly confides in him that her mother, single parent Cindy, is a source of embarrassment: Cindy behaves like a child, maintaining the position of a teenager and peer to Brooke and committing acts like dancing to the latest trendy music and going out with Brookes own friends. Grover invites Brooke to send Cindy into his basement, which she does and which finally secures Grover the girl of his dreams. The kids take over the house, while the adults in the basement rant and protest and make repeated attempts to escape. However, Grover eventually gets them all in line and reminds them why they imprisoned their parents; they actively start counseling the parents, trying to get them to improve their attitudes. Over the course of time, the parents begin to repair things: Vic learns that Louise thinks she cant be accepted by his children, but when Donald attacks Matt she saves him and he thanks her by calling her mom, putting her at rest; Gwenna manages to assert herself as Donalds equal partner; and Cindy, with help from Gwenna, manages to mentally grow up and be more adult-like.However, an ex-policeman neighbor starts to snoop around the Beindorfs home, suspicious of their prolonged absence and the antics of the children present. Also, Grover receives a shock when a man claiming to be Janets lawyer appears with divorce papers. This leads to Ned breaking off speaking with Janet, and an angry Grover leaves the house. He later returns, and states the house arrest was a failure; Brooke and the others tell him even if they couldnt have their parents to count on, theyll always have each other. The ex-cop neighbour arranges a police assault on the house, and all the parents are freed. Donald attempts to sue and imprison Grover, but the children and Gwenna force him to back down.The film ends with an epilogue from Grover: Donald and Gwenna separate, but remain friends and open a law firm together; Vic and Louise stayed together and are expecting a child; Cindy began actively dating men her own age; and Brooke officially became Grovers girlfriend. As for Ned and Janet, they reconciled and went on a long-overdue second honeymoon to Hawaii. They also made their children swear never to lock them in the basement again. Grover and Stacy complied if anything went wrong again, they had the attic...