It is late Summer 1946 on the Frake family farm in Brunswick, Iowa. The Frakes are preparing to leave for the Iowa State Fair. Father, Abel, is confident his prize boar, Blue Boy, will win a blue ribbon, but neighbour, Dave Miller, isn't so sure. He makes a $5 bet that something is bound to go wrong for at least one member of the family. Abel accepts the bet. Abel's wife, Melissa, has her heart set on a blue ribbon for her mincemeat. Son, Wayne, is disappointed that his girlfriend has to stay at home. Daughter, Margy, is feeling down and doesn't understand why. Her suitor, Harry, pressures her for an answer to his long-standing marriage proposal; she agrees to give him an answer when she returns home.
So it's off to the Fair. Arriving at the midway, Wayne heads straight for the ring toss where he is hustled by the barker. A glamorous woman intercedes on Wayne's behalf He is smitten before he even gets to know who she is. At the beer tent, Abel and his cronies sit around trading stories about their loved ones.Meanwhile, a young and somewhat world-weary reporter, Pat Gilbert, arrives to cover the Fair. He sets his sights on Margy, who remains aloof until he begins to win her over. Wayne happens by the Starlight Dance Meadow in time to catch the floor show. The star attraction is Emily Arden, the woman he met earlier in the day. Over a beer she tells Wayne she is determined to become a Broadway star. He asks for a date, charming her with his boyish enthusiasm. She agrees, but on her terms.
The next morning, Margy bemoans the life Harry is planning for them. Abel is so excited at the prospect of victory and winning his bet with Dave Miller that he proposes an evening of family fun and dancing.
At the Exhibit Hall that afternoon the pickles and mincemeat are being judged. As it happens, Melissa's mincemeat has been amply spiked, which sends the judges into giggles of delight. She wins the blue ribbon and a special plaque. Pat is on hand to capture the euphoric moment. From a moonlit hill, Wayne and Emily watch the fair below. He has fallen head over heels, but she remains cautious.
At the Starlight Dance Meadow fairgoers gather for a dreamy waltz. Abel and Melissa dance romantically, Wayne and Emily arrive with a distinct glow, and Pat and Margy share a first tentative kiss as Harry arrives unexpectedly.
It is the final day of the Fair. Despite Harry's presence, Pat and Margy are clearly growing fonder of each other. As Margy rushes off to cheer for Blue Boy, Pat's friends help him realise he is no longer his old self. Blue Boy is finally declared the winner of the hog-judging competition, and Abel cannot contain his joy.
Pat learns he has landed the Chicago job interview he has been waiting for, but it means catching the next train out of town. Reluctant to leave Margy in the lurch, he races off just as she arrives for their date. The scene shifts to the Starlight Dance Meadow and Emily Arden's final performance. Both women realise their relationships are in trouble. Later that night Wayne proclaims his love for Emily, but she breaks it off. Back at the family campsite, Abel and Melissa are basking in their victories. Melissa is concerned about the children, but Abel assures her that they have each other. Wayne staggers in having drowned his sorrows. In his stupor, however, his thoughts turn to his girl back home. Understandingly, Abel helps his son 'Walk it off'. On the darkened midway Margy is still waiting for Pat. The Fair is almost over, and she realises he is probably not coming. Harry enters, pleading to Margy to accept his proposal. She can't - she realises she just doesn't love him.
The Frakes return home. There is a spread in the local newspaper chronicling their adventures at the Fair, written of course by Pat Gilbert without any of them knowing. Dave Miller reminds Abel that the $5 bet hinged on everyone having a good time at the Fair, and whilst Wayne is thrilled to be home and is making big plans with his girlfriend, Margy seems a little low. At that very moment, who should arrive but Pat, out of breath and full of apologies, but he has just landed the job in Chicago and wants Margy to join him there. The lovers rush into each other's arms as Miller reluctantly hands over the five dollars.