At breakfast, Bev pulls out her butter sculpture from when she was crowned Princess Kay and tells Sadie that she’s made it into the Princess Kay of the Milky Way competition. A spot opened up for her because another girl’s family lost their farm making her ineligible to compete. Bev has secured Sadie an interview at the Fair and goes off with her to go prepare. With the kitchen empty, a small alien hand drags the butter head off the table.

Eugenia and Sadie sit on the roof. Eugenia is listening to her radio show and using a homemade radio telescope to listen to the stars. Sadie seems nervous about the Princess Kay competition. Eugenia reassures her, and they tease each other a bit. Sadie is also feeling sad that her dad is overlooking her and focusing on her brother Emmett as the next leader for the farm.

Emmett is out in the barn playing the guitar and trying to sing like Johnny Cash. Dean comes in and tells Emmett that he needs to be ready to take over the family farm should anything happen to him. It is implied that Emmett will be the one to take over the farm because he is the only boy. Emmett says that Dean can count on him, and they should not sell the farm.

A bright light emanates from the barn that is strange and otherworldly. The siblings go to investigate. Sadie encounters an alien in the barn. Eugenia and Emmett show up as well. The alien is eating Bev’s butter sculpture. They argue about what to do with the alien and then realize that it’s morning. Beverly and Dean start to pack the car, and the siblings try and keep the alien out of view. The alien eventually sneaks into the trunk, and the siblings can’t pull it out. The next thing they know, they’re all at the State Fair.

Beverly opens the trunk to discover that the alien ate most of her baked bars that she was entering in the Fair. She didn’t see the alien, though, so Eugenia takes the blame. Beverly is devastated and grounds Eugenia, saying she has to stay by her side for the whole fair.

It’s decided that Sadie will watch the alien for an hour before her Princess Kay interview while Emmett takes their cow Mootilda to the 4-H pens. Sadie decides to name the alien Louise.

Meanwhile, Dean is admiring an old tractor when Chock Hubbard, the industrial farm owner, reminds Dean of his generous offer to buy his farm. Chock also says that he thinks extraterrestrials may be the reason for the strange happenings on the nearby farms. Chock gives Dean six tickets to the Johnny Cash Show at the Grandstand which Emmett is dying to go to. Taking the tickets feels like a bribe, but Dean ends up taking them.

Back in the 4-H pen, Emmett is working on a new song in the style of Johnny Cash. Palmer, the teen in the next cow stall, tells him how much he dislikes country music. Palmer then comes into Mootilda and Emmett’s stall and says that Mootilda is not a prize-winning heifer. Emmett gets competitive and tells Palmer that Mootilda is the finest breeding heifer and Palmer and his cow Skim will not stand in their way.

Sadie takes Louise on a dairy tour of the fair and sings “Minnesota’s Known for Dairy.” Sadie and Louise end up at the meet-up point, the All-You-Can-Drink Milk Tent, but Emmett is nowhere to be seen. Sadie has to go to her Princess Kay interview, so she asks Louise to stay put at the tent until Emmett comes to get her.

Bev is in line with the other Minnesotan ladies to turn in her bars for judging. Eugenia overhears other fairgoers talking about a girl drinking up all the milk at the All-You-Can-Drink Milk Tent. Eugenia knows that it must be the alien, so she tells her mom that she has to go to the bathroom. Bev lets her go.

Bev’s rival, Jean Holtzmeier, tells her that her husband saw Dean talking to Chock Hubbard. Jean remarks that she didn’t know Bev and Dean were going to sell their farm. This is news to Bev, and she feels blindsided. Bev gets to the front of the line but doesn’t end up submitting her bars. She covers by saying she forgot to dust them with confectioner’s sugar and walks away embarrassed.

Louise is at the milk tent drinking her 100^th cup of milk and drawing a crowd of onlookers. Eugenia manages to get her away. Chock tries to stop them because he is suspicious of Louise. Eugenia manages to get away, but Chock takes Louise’s milk cup as evidence. Louise gets distracted and walks off. Eugenia starts to chase her, and we see a shadowy figure emerge and start to follow her.

Sadie is at her interview, and it’s not going well. She is trying to emulate her mother’s responses, and they’re not landing.

Meanwhile, Emmett and Palmer are exploring the fairgrounds when they run into Dean. Dean tells Emmett about the tickets to the Johnny Cash concert, and Emmett says that he’s no longer a Johnny Cash fan. Dean wonders if Emmett will change his mind about taking over the farm too.

Sadie tells the interviewer that she wants to show other young farmers that this life is tough but fulfilling. She would advocate for more support from the federal level with subsidies, competitive pricing, and more incentives for consumers to buy local. She shares that she wants to run the family farm.

Eugenia follows Louise onto Ye Old Mill, a flume ride. The shadowy figure hops on just behind them. On the ride, Eugenia discovers that the shadowy figure is a kid about her same age. He introduces himself as Upton F. Overton, the radio host that Eugenia listens to! At the end of the ride, Beverly is there to yell at Eugenia. Upton insinuates that Louise is his younger sister and whispers to Eugenia that he’ll find her later. Beverly drags Eugenia away, and Upton takes Louise.

Chock Hubbard receives a call from one of his employees. They’ve run some analysis on the milk cup that he collected, and they tell him that whatever the cup came into contact with is not of this earth.

Eugenia and Beverly are at the Princess Kay coronation ceremony. The ceremony begins, and the emcee announces the runners-up. Sadie does not win and isn’t even one of the runners-up. She puts on a brave face as everyone cheers for the winners. Dean and Emmett come in after having missed it, and we enter intermission.

Sadie is in the rotating, refrigerated case in the Dairy Building getting her head carved out of butter. Her dad helps her out of the case. Sadie is clearly upset that he missed the coronation, and she tells him that he doesn’t have to do everything by himself. She leaves, and Dean starts to realize that Sadie may be interested in running the farm.

The siblings are in the 4-H pen while Sadie is getting Mootilda ready for showing. Emmett and Eugenia are arguing about Eugenia’s decision to let Upton take Louise. Emmett doesn’t say it, but he’s upset that he can’t pursue music and has to take over the farm. They tussle, and Eugenia’s radio telescope gets broken. Emmett storms off. Sadie exits with Mootilda to do the 4-H show. Eugenia searches on her own throughout the fair for Upton and Louise.

Emmett and Palmer eat Sweet Martha’s Cookies together, and Palmer tries to show Emmett that there’s interesting people and things happening all around him. He encourages Emmett to sing about himself and his experiences; he doesn’t need to pretend to be anything other than who he is. Palmer leaves to go to the 4-H competition, and Emmett finds Louise and Upton! He chases after them, and we see Chock Hubbard watching from behind a newspaper.

At the 4-H competition, Mootilda and Sadie win! Chock congratulates Sadie and insinuates that he knows about the alien. He wants their land, and if Sadie can help convince her dad to sell it to him, he will keep their secret safe. Even though she doesn’t want to, Sadie tells her dad to sell the land, catching him off guard.

Sadie, Emmett, Upton, and Louise all gather together. Upton thinks that Louise’s home planet has sent her a message and is awaiting her response. Sadie thinks that it doesn’t matter because they’ve lost the farm due to Chock’s threats. Upton gives them some space to talk, and Emmett leaves after telling Sadie that she needs to pull it together and be the Sadie that he knows – the one that would stick up for herself and her family.

Sadie is left alone with Louise. Louise makes the ground shake. There’s a flash of light, and Sadie and Louise disappear.

Bev expresses how frustrated she is with Dean for not telling her about Chock’s offer. Bev admits that she didn’t end up entering her bars in the competition. They agree to tell each other everything moving forward. They decide that selling the farm might be the best option for the family. Dean finds Chock to tell him that he has a deal while Bev goes to find the kids.

Emmett finds Eugenia at the base of the Space Tower and sings the new song he wrote about how he feels like he’s an alien on the prairie. Eugenia feels that way, too. Emmett tells her that they found Louise and Upton, and they realize that they can use the Space Tower to transmit a response to the signal from space.

Sadie and Louise appear in a void of space. Louise appears as Eugenia to lessen the strain on Sadie’s brain. Throughout their conversation, Louise takes the form of all of Sadie’s family members. This is a form of communication Louise can use, but it runs the risk of melting Sadie’s brain. Louise felt a kindship with Sadie and was intoxicated by her passion for her farm and Minnesota. Louise did not want to return to her planet, but Sadie’s love for her home and her willingness to sacrifice her desires to protect it made Louise appreciate hers more. She feels ready to return home and inherit planetary rule. Sadie thanks her and curtsies as Louise is a real-life Princess Kay of the Milky Way. There’s another flash of light, and they disappear again.

Sadie wakes up surrounded by Beverly, Emmett, Eugenia, Louise, and Upton. She tells her mom everything and that they have to stop her dad from selling the farm to Chock Hubbard. While Sadie, Beverly, and Emmett work to sabotage the deal, Eugenia and Upton will work to send Louise back home. Emmett says Palmer and the 4-H kids can help too.

Step one of the plan is to draw the crowds away from the Space Tower. Everyone will be going to the Johhny Cash concert, but he doesn’t go on for another hour. Emmett will go on as an opening act. Emmett goes onstage and shreds on his guitar.

Chock and Dean are going over the paperwork. The 4-H kids come by with a wheelbarrow full of mud and manure. They start throwing mud at Chock yelling, “mud fight!” Chock chases after them.

Upton fixes Eugenia’s radio telescope and alters it to become a radio transmitter. Louise and Eugenia ride up in the Space Tower. Once at the top, Louise sings out her signal.

Sadie and Dean finally talk to each other, and both say that Sadie should take over the farm. They hug.

Chock comes up and tries to get the crowd to turn on the Berglunds for harboring an extraterrestrial. Beverly and Dean gaslight him. Sadie argues that Chock is the real danger since he’s been buying up all of the family farms. The crowd agrees. Chock gets run off by the 4-H kids imitating animals.

A bright light shines down on everyone. It’s time for Louise to go. The Berglunds and Louise do a classic Minnesotan Long Goodbye. Eugenia and Louise dub Sadie the true Princess Kay of the Milk y Way for being the first inter-planetary goodwill ambassador for the Minnesota dairy industry. Louise levitates up the beam of light to the space craft above, and it takes off.

Back at the farm, we see that all is well with the Berglund family. Sadie took over the farm and now has a daughter of her own that she has been telling the story to. She hopes that the Berglunds will always be there on that land looking up at the stars.