Justin walks happy to find out that his collectible Captain Jim Bob Farmhouse Space Command Module is apparently worth $300. Jerry comments on how it can't that valuable considering Justin fell on it and squashed the Space Cows. Alex walks in with some stuff she found while cleaning out the basement, including Justin's old scooter, Jerry's football phone, and Theresa's Shawn Cassidy poster (which has lipstick on it). But Jerry is suspicious on why Alex would be cleaning out the basement. They all go down and discover that she wants the space for her own art studio. Justin says that he should have the basement to store his Captain Jim Bob Farmhouse Space Command Module. But the parents tell them that nobody is getting the basement.
Later, Harper comes by the Sub Station looking sad and says that she's moving. The Russos are shocked, and Harper tells how her dad got transferred to Pittsburgh, and they have no family in town that she can stay with (or at least ones they know where to find) so she can finish school. Alex then suggests that Harper could move into the basement and stay with them. After Jerry and Theresa agree, Harper calls her mom on her cell phone, and apparently they planned the Russos inviting her to live with them the whole time.
Alex starts helping Harper move in, or at least having her carry in most of her stuff. Alex still wants to keep her art studio in the basement but Harper refuses to sleep in the corner. In the basement, the two find an old doll house they used to play with when they were young. Alex says how she wishes she knew about magic when she was 5 years-old, otherwise she would have shrunk herself down and lived in it. This gives her an idea, and uses magic to shrink all her art supplies down into the doll house to make her very own little studio. Meanwhile, Justin decides to sell his Captain Jim Bob Farmhouse Space Command Module because he doesn't have the space to keep it in. A guy named Randy who heard about Justin selling the collectible item comes by and offers to buy it, but only offers Justin $75, seeing how the space cows have obviously been squashed.
Harper has now completely moved into the basement. Alex comments on all the headless mannequins in her room which hold all her outfits, asking if they're going to freak her out at night. Harper then goes to get the heads, while Alex goes inside her art studio. Jerry and Theresa come down to finish cleaning out the basement. They find the old house and decide to get rid of it, while Alex is still inside! While Theresa carries the doll house up the staircase, Alex accidentally drops her wand out the door.
Jerry and Theresa then meet a little girl named Olive who lives in the neighborhood. Olive is very fond of the doll house and asks if she can have it. Harper tries to take the doll house back, but Jerry and Theresa tell her it now belongs to Olive. Harper looks inside to find that Alex is still in there. Harper says she'll go get Justin but Alex tells her she wants to figure this out on her own. Despite Alex's wishes and knowing that Alex won't really be able to fix this, Harper goes straight to Justin who is busy restoring his Captain Jim Bob Farmhouse Space Command Module back to it's full $300 value. Harper explains to Justin that Alex is in trouble but doesn't want him to help her. A little confused, Justin decides that he will help Alex by not helping her. Harper says that if he wasn't so cute, she would be mad at him right now.
Olive has already started playing with her new doll house, and apparently has mistaken Alex for a doll by putting her in a little dress. Harper asks Olive if maybe they can be friends and set up a play date, so she can save Alex later. But Olive tells her that her parents have told her to stay away from the "weird girl", which is apparently Harper. Meanwhile, Justin is about to give the Captain Jim Bob Farmhouse Space Command Module to Randy but, as part of his plan, has Max pretends to be a stranger who is willing to buy it for a bigger price, and Randy starts bidding up to $400.
Harper talks to Alex inside the doll house, and Alex is upset that Harper can't find her wand and has been getting her hair pulled out by Olive who keeps using her cat's brush to brush her hair. ("The dress is bad enough, I don't want to be a bald doll!") Alex then decides to let Harper get Justin, but Harper admits that she already did. Although upset with her, Alex understands why Harper did it, but is still upset when she hears that Justin is not going to help her. Also hearing how Justin just sold his Captain Jim Bob Farmhouse Space Command Module for a lot of money, Alex decides to have Justin pay to get the doll house back from Olive.
Reluctantly, Justin gives up all his money and gets the doll house back, and in anger, he starts shaking the doll house while Alex is inside. Down in the basement, Justin brings her back to normal and Harper asks Alex not to change out of the dress until she gets her giant teddy bear and tea set for a tea party. Justin is still mad at Alex, but Alex eagerly tries to start an argument about it, seeing it as a bond they have. After Justin snaps at her, Alex jumps happily and hugs him, to which Justin responds by squeezing her very hard.
In the end, Max sells the collectible plate of garbage he showed Justin earlier to Olive, who bought it with the same $400 Justin gave her for the doll house. Justin is surprised and Max offers to buy him a sandwich, even though they can get sandwiches at the Sub Station for free!