In the small town of Candy Rock, rubbish collector and amateur inventor Artie Pinsetter tinkers with “Max,” his thinking machine. Artie owns the only independent business in a town controlled by Raven Rossiter, who has decided to expand his venue by running for governor. One day, while Raven is being interviewed by television personality Bill Burton, Artie walks into the Rossiter-owned radio station to buy more radio parts and tubes to implant in Max. Raven agrees to extend the cash-strapped Artie credit in exchange for his promise to stop dating Raven’s niece Emmy Lou. Later, at the Rossiter home, Emmy Lou sings Artie’s praises to her aunt May. When Artie arrives to pick up the trash, Emmy Lou climbs into an empty trash barrel that Artie loads onto his truck. Artie then drives to Dinosaur State Park with his dog Corporal. After climbing out of the barrel, Emmy Lou asks Artie to marry her, and when Max forbids the union, Emmy Lou angrily runs into a nearby cave. Minutes later, she emerges as a woman who is now thirty-feet tall. A panicked Artie drives to the Rossiter home to inform Raven that Emmy Lou has “gotten big.” Thinking that Artie means she is pregnant, Raven, fearing a scandal, arranges for Magruder, the justice of the peace, immediately to marry Emmy Lou and Artie. On the drive back to the park, Artie stops at a surplus store to buy a parachute that Emmy Lou later fashions into a wedding dress. Magruder, who is blind without his glasses, is unable to see Emmy Lou until he asks for a kiss from the bride. When Emmy Lou looms over him to proffer her cheek, he flees in fear. That night, Artie studies his colossal bride. The next morning, when Emmy Lou awakens and announces that she is ravenous, Artie hurries into town to forage for food. When Artie blurts out that Emmy Lou is now thirty-feet tall, Raven, concerned that the news may damage his campaign, arranges for a caravan of trucks to deliver food to his starving niece and gives her a barn located ten miles from town as a honeymoon cottage. After loading Emmy Lou onto a flatbed truck, they drive her to the barn where she asks to take a shower. As Artie sprays her with a fire hose, she begins to grow again. Meanwhile, a series of war games are being staged at the park, and when a military helicopter flies over the barn, the pilot spots Emmy Lou protruding from the roof. The pilot’s addled report about a giant woman causes the general in charge to cancel the games. Peeved, the Pentagon demands an explanation, and when a sergeant explains that they have sighted a monster, the Pentagon issues an alert about invaders from space. Meanwhile, at the Booster’s Club, a benevolent organization headed by Raven, Raven is boasting of his achievements to Burton when Artie bursts in to tell him that his niece is still growing. Flustered, Raven gets rid of Artie by making him a Booster and giving him a fancy new car. As Artie drives off, Jackie Delaney, the town flirt, jumps into his car. When they reach the barn, Emmy Lou jealously bellows at Jackie to “keep her hands off” Artie. After Jackie runs off screaming, Emmy Lou, angered by Artie’s “infidelity” and her uncle's insistence on controlling her life, decides to go to Candy Rock where she climbs atop a building and cackles down at the citizenry. Desperate, Artie returns to the park and asks Max for help. Meanwhile, the military has been trailing Emmy Lou and passes her coordinates along to the Pentagon. Emmy Lou returns to the park just as the military launches a series of missiles at her. After Max sends a signal that causes the missiles to collide, the troops arrive armed with bazookas. To avoid the weapons, Artie orders Max to take them all back in time, and after Max sends them to the era of the Civil War and then the Stone Age, Artie realizes that Max has finally proved its genius and asks the machine to shrink Emmy Lou. After Max shrinks Emmy Lou into a miniature woman, the soliders arrive and demand to see the giant from outer space. Raven then comes to the park with Burton, and when Artie boasts that he has developed a machine that can bend time and space, Burton invites him to appear on his show instead of Raven. After the soldiers confiscate Max, Emmy Lou returns to normal size and Corporal, now a giant, tags along behind them.