The Beindorf family, Ned Beindorf [Kevin Pollak], Janet Beindorf [Jamie Lee Curtis], Grover Beindorf [Kyle Howard], and Stacy Beindorf [Amy Sakasitz], seems to live a deceptively calm life in the suburbs of Defiance, Ohio. In truth, Ned and Janet are not happy and are edging toward separation, though they insist to Grover and Stacy that it isn’t a divorce. Their uneasy closeness glows through the small, quiet tensions of a household that keeps pretending everything is fine.
Grover and Stacy attempt to fix their parents’ marriage by recreating Ned and Janet’s Hawaii honeymoon right in the basement, a playful but futile gesture that only underscores the distance between the couple upstairs. When the basement experiment fails to bring joy, the siblings decide to escalate their plan: they tell Ned and Janet there’s a new surprise for them upstairs and then seal the door shut, vowing to keep it locked until the adults resolve their problems. The next day, Grover shares the tale with his best friend Matt Finley [Mooky Arizona], who is curious and a little alarmed, while T.J. Krupp [Herbert Russell], the local wealthy bully, overhears and becomes intrigued.
Matt Finley goes to the Beindorf house to see Grover’s handiwork and is impressed by the ingenuity of the makeshift trap. T.J. Krupp, meanwhile, doesn’t stop at observation—he installs a newer, more secure door to keep Ned and Janet in. What begins as a small, secret experiment among children quickly spirals into a larger, more organized capture: Matt’s father Vic Finley [Wallace Shawn] and T.J.’s father Donald Krupp [Christopher McDonald] are brought into the scheme, each with their own complicated marital histories. Vic has never kept a wife for long and is currently with Louise Finley, while Donald treats his wife Gwenna Krupp with little respect. Matt also brings Cosmo the bulldog and two younger brothers, Jimmy and Teddy, and T.J. contributes his boa constrictor, Spot, turning the house into a chaotic family campground inside the basement. When Grover asks what’s going on, T.J. deadpans, “Our parents could be down there for months!” and the line becomes a chilling reminder of how far this plan has gone.
As the kids wrestle with the moral weight of their actions, Ned and Janet nearly persuade Grover to unlock the door, but Donald Krupp threatens legal action if he tries. The situation widens when Grover discovers that his crush Brooke Figler [Jennifer Love Hewitt] is facing her own parental drama: her mother Cindy Figler [Jennifer Tilly] acts awkward and intrusive, even meddling in Brooke’s social life. Grover invites Brooke to join the plan, and Brooke’s presence shifts the dynamic—Courtship, loyalty, and fear all collide in the basement as secrets begin to surface.
Emotion and empathy start to creep into the children’s resolve as they work to understand each other’s problems above ground. The kids confront their own grievances while trying to figure out a way out of the basement, but they also learn to listen and cooperate with their parents. Eventually, a staged, collective decision is made to surrender to the authorities, led by Chief Rocco [Ray Walston], who arrives to restore order and safety. The kids’ ruse ends with Ned and Janet freed, and the families stepping back from the brink of upheaval.
In the aftermath, the Beindorf clan finds renewed footing: Ned and Janet reconcile and embark on a second honeymoon to Hawaii, revisiting the happiness they briefly lost. Vic and Louise’s marriage endures beyond the two-year mark, and they even expect another child, a sign of life moving forward. Donald and Gwenna divorce, though Gwenna returns to law school and the two rebuild their professional lives together, opening a new law firm. Cindy begins dating other guys, allowing Brooke to reclaim her own social space, and Grover and Brooke become a couple, sharing a bold kiss in front of their classmates. Grover ends with a pragmatic thought about the future: if Ned and Janet ever consider divorce again, he might just lock them in the attic as a last resort, a reminder of how fragile family dynamics can be and how far love and understanding must travel to heal old wounds.
