Nobita is in Shizuka's room where she tells him that her doll Jenny has been feeling sad and asks him what he thinks. Nobita examines the doll and tells Shizuka that Jenny doesn't look any different than before, causing Shizuka to coldly snatch Jenny from him. She explains to him that Jenny has been feeling sad as Jack, another one of Shizuka's dolls and Jenny's boyfriend, has gone missing and she doesn't know how or why. After hearing her story, Nobita states that he finds the whole story of Jack disappearing all of a sudden to be ridiculous. He starts deducing that Shizuka might have left him somewhere after playing with him or her mother hid the doll away from her so that she could focus on studying. While explaining this, he's completely unaware that Shizuka is seething and in a fit of rage, she yells at him to get out.
As Nobita heads back, he is annoyed over Shizuka's childish behavior and how she's showing that much emotion and passion over her own dolls than her friends. As he continues walking, he runs into Dekisugi who tells him that Shizuka called him over to help her out with something. He asks Nobita if he knows anything about her problem and Nobita tells him he doesn't and to find out from her instead. As Dekisugi bids farewell, Nobita gleefully thinks that he too is going to face Shizuka's wrath, but then remembers that he's smarter than him. Nobita heads back home and to his room to ask Doraemon for help. As soon as he enters his room however, he is met with a taiyaki that's floating in the air. The taiyaki eventually catches hold of a bait from a fishing rod which Doraemon used to capture it. Nobita asks him how the taiyaki floated in the air and Doraemon introduces him the Animating Microwave gadget. With the Animating Microwave, a person can make an inanimate object come to life for a few minutes, and Doraemon demonstrates the animating taiyaki as an example, which then escapes. Doraemon chases after it while tossing the gadget. Nobita snatches the gadget and decides to use it to help Shizuka out with her missing doll.
Back in Shizuka's house, Dekisugi deduces that someone must have taken Jack away as Jack could have not disappeared just like that. Shizuka asks him who could have done such a mischievous thing, and Dekisugi concludes it's not a person but rather a stray cat who might have taken it away after trying to eat it. He comes up with the idea to make missing posters for Jack and post them all throughout the neighborhood, while Shizuka goes to the neighbors and inquire about Jack's whereabouts. While they're outside, Nobita arrives to Shizuka's house, only to be greeted by her mother who tells him that Shizuka and Dekisugi went out and haven't come back. She invites him over to wait for them and Nobita accepts the invitation and heads into her room. As Nobita gets jealous that Shizuka decided to get Dekisugi's help instead of his, he notices Jenny and decides to use the Animating Microwave on her to find out about Jack's whereabouts. After using the gadget, Jenny comes to life and begins to cry, much to Nobita's surprise, and then she runs off with Nobita frantically chasing after her.
Meanwhile, Shizuka asks various neighbors if they've seen Jack lying around somewhere, but with no luck. As she walks by, Dekisugi catches up and tells her that he's done posting the missing posters throughout the neighborhood. As Shizuka starts to express doubt over finding Jack, Dekisugi reassures her that they will find him thanks to the posters and to have some hope. He takes his leave with Shizuka thanking him for his help. Elsewhere, Nobita loses sight of Jenny and begins to look for her in panic. He eventually runs into Shizuka who asks him what he's doing and he explains to her what happened. Shizuka chastises him before crying over losing Jenny and when Nobita tries to pacify her, she slaps him in the face for his blunder.
Back home, Nobita explains the whole story to Doraemon, who isn't surprised that Shizuka slapped him. He tearfully pleads to Doraemon to help him out, as he does not want Shizuka to break her friendship with him. Taking pity over Nobita, Doraemon agrees to help but on the condition that Nobita will never use his gadgets without his permission ever again. Nobita agrees, and they both head out to search for Jack. They ask a gray cat if they've seen the doll, and the cat tells them it saw a stray cat take the doll to the empty lot. They head to the empty lot where Nobita finds Jack's shoe and soon enough the stray cat arrives. Doraemon asks the cat what happened to the doll and it tells them that a girl came and took the doll away. With no way to find the girl's house, Nobita and Doraemon wander around until Nobita spots a toy dog. He asks Doraemon to give the Animating Microwave, and he uses it on the toy dog so that it can come to life and locate the girl who took Jack. The toy dog leads them into a house, where the girl who lives there confirms that she does have a male doll. Nobita and Doraemon celebrate finding Jack before the girl explains that she won't give Jack back as he became friends with her own doll Betty and lashes out on them. Just then, Jenny arrives and heads inside the house with the girl, Nobita and Doraemon following her. They find Jenny in the girl's room where she embraces Jack while there's another doll, who is Betty. Nobita and Doraemon are happy that Jenny reunited with Jack, but the girl refuses to accept this situation. Nobita tries to reason with her, telling her that two dolls belongs to his best friend (Shizuka) and uses the Animating Microwave on both Jack and Betty. Jack runs to Jenny and the two reunite while a heartbroken Betty goes to the girl, who consoles her as they both cry. Nobita states he feels bad for Betty, while Doraemon tells him that Betty will someday find her true love, to which Nobita agrees.
It's not shown whether Nobita restored his friendship with Shizuka or not, but it can be assumed that he returned Shizuka's dolls back to her and they made up off-screen.
