Wayne Szalinzki is back again but only this time he decides to use his infamous shrink machine just one more time. Wayne accidentely ends up shrinking himself and his brother Gordon! Meanwhile, when Gordon's wife Patty and Diane were going on a vacation they went back to the house when Patty suddenly realizes she forgot Mitch's medicine for his potassium deficiency. When they were about to leave, they decide to sneak into the attic and surprise the men, but the shrink ray is activated once again, and the ladies are shrunk as well! So the team must be very brave of disgusting household insects the size of dinosaurs and more in their biggest adventure to get their children's attention!