Roman and his family are broke. He wanted Chet's money to continue living their lifestyle instead of investing it. After rescuing Roman's daughters and fighting off "The Bald-Headed Bear", Chet and Roman make peace with each other.
Chet Ripley (John Candy), his wife Connie, and their two teenage sons are on a family vacation at a lake resort in Wisconsin. Just as they are settling into their cabin, Connie's sister Kate (Annette Bening), her investment broker husband Roman Craig (Dan Aykroyd), and their twin girls unexpectedly join them. Chet and Roman don't get along very well, but Chet tries to make the most of the situation. On their first night together, Chet tells a fireside story of a bear he encountered when he and Connie last vacationed at the cabin, which resulted in Chet shooting the bear's fur off of it's head and is now referred as "The Bald-Headed Bear".
Tensions rise between Chet and Roman the next day following an incident involving Chet getting dragged behind Roman's speedboat while attempting to waterski, and later Chet getting hit by an errant tee shot from Roman. Later, as the tension between the two is at it's highest, Roman reveals the reason they came to join Chet and his family. Roman has a great investment opportunity, and despite the problems between them, he still wants to cut Chet into it. All he needs is $25,000 to get it going. Chet is hesitant to hand over that much money, but he and Connie agree to pay up.
As Roman and his family are driving home, Kate reveals that Chet and Connie cashed out their life savings as well as the boy's college funds to get into this investment. A suddenly guilty Roman turns around and goes back to the cabin, where is tears up the check in front of Chet. Roman tells everyone, including his wife and kids, that there is no investment opportunity. Roman was fired from his job and has no money, and he needed Chet's money to continue living their lifestyle. Both families proceed to get into a heated argument, and no one notices the girls wander off. They find and fall into an abandoned mine shaft.
Soon the girls are discovered to be missing, and Chet and Roman go looking for them. They eventually find the mineshaft, and while Chet goes to get a rope, Roman crawls into the shaft and rescues the girls. Chet returns, not knowing the girls are safe, and throws the rope into the shaft. He pulls out a bear, and it's "The Bald-Headed Bear." The bear chases Chet back to the cabin, and just as it looks like the bear is going to maul everyone, the resort's owner shows up and shoots the bear in the backside, knocking off it's fur. The bear is now bald on both ends.
Following the rescue and the incident with the bear, Chet and Roman make peace with each other. Roman tells Chet "race you home", and he and his family drive off. The movie ends with Connie telling Chet that she invited Kate and her family to move in with them until they can get back on their feet. Chet then quickly packs up the car and they start racing Roman back home.