Our heroes and Team Rocket both seek shelter from a downpour in an old, abandoned mansion. When lights come on and doors close behind them, they’re convinced the mansion is haunted—and because neither of the two groups knows the other is there, they keep scaring each other with their startled screams!
When our heroes explore the house and encounter a mysterious being with glowing eyes, Ash, Serena, and Clemont are terrified—but Bonnie runs after it to find out what’s going on, and ends up making a new friend: a Psychic-type Pokémon named Espurr! She realizes that Espurr has been responsible for all the strange happenings in the house, and that it’s keeping them from leaving for some reason. Espurr shows her the lovely pendant it’s wearing, and points out the same pendant in a portrait of an older woman, but Bonnie can’t figure out what it wants.
Ash, Serena, and Clemont go searching for Bonnie and run into Team Rocket instead. They accuse each other of being responsible for the “haunting,” but when they meet up with Bonnie and Espurr, they quickly figure out what’s going on, and Meowth offers to translate for Espurr so it will let them leave the house.
It seems the woman in the painting used to take care of the wild Espurr, feeding and playing with it when it came to her mansion. She even let it wear the precious pendant, a gift from her husband. But when it came back to return the pendant, the woman was gone and the house was empty. It’s been waiting in the house ever since, hoping its friend will come back for her pendant—and now it wants our heroes to help find her!
Jessie, James, and Meowth have another idea: they want to catch Espurr instead. They attack, but it quickly sends the villains blasting off again. Ash and Clemont are promising Espurr that they’ll help it find the woman who lived in the mansion when the new owner of the house arrives! Her name is Elise, and the woman who took care of Espurr was her grandmother, Lacy. She tells Espurr the sad news that Grandma Lacy passed away, and offers to take it to the cemetery so it can say goodbye to her. Elise also announces her plans to renovate the old house and move in herself, and says Espurr is welcome to come and play any time. It’s a bittersweet ending to Espurr’s long quest, as our heroes say their farewells and continue their journey to Cyllage City.
Thunder flashes and rain falls on an old mansion; inside, a painting shows an old woman wearing a green pendant. Outside the mansion, Ash and his companions are getting soaked. The run for cover underneath the mansion's porch. A thunder bolt frightens Bonnie and sends her reeling back into the door, which creaks open, and Ash suggests the group take shelter inside. Bonnie runs inside eagerly and yells hello, but no one answers, even after Clemont politely knocks. What they don't notice is that watching them from on the top of the stairs is a mysterious Pokémon, with the green pendant around its neck. After several more unanswered calls, the group deduces the mansion is probably uninhabited. Bonnie suggests that they stay for the night, and the others reluctantly agree.
Clemont insists the others (except Bonnie) are scared only because it is dark, and goes to turn on the lights. The chandelier lights up and the others thank him, but he tells them that it wasn't him who turned the light on. As the others wonder nervously, Clemont hurriedly attempts to justify the occurrence by saying that there must be sensors that can detect human presence. The group attempts to laugh it off, but Serena suggests the place is cursed, she then covers her mouth and asks "Did I just say that?" Ash shudders when Serena makes the statement and quickly loses his confidence and suggests that maybe they should take shelter outside after all. Just as Clemont agrees, the door shuts and locks behind them. Clemont again uses science to explain what happened, but when Serena mentions that a monster might live in the mansion, and she again covers her mouth and asks "Did I just say that?" Clemont decides to look for a way out, saying he can't trust "what is not scientifically proven." Ash agrees and the group begins to look for an exit.
Outside, Team Rocket runs to get out of the rain and come to the mansion, and Jessie decides it looks like a good rain shelter, though James is hesitant. Jessie knocks on one of the back doors and after James expresses his doubts, Jessie says that the mansion will be perfect as a front line base for them in the Kalos region. A window opens wide after the door won't budge, and Meowth and James follow Jessie inside. Jessie, like the children, guesses that the house is vacant, and the window they came from closes behind them. As Jessie wonders where the light switch is, the light turns on. James thanks Meowth, but Meowth insists it wasn't him, and that the mansion must be automated. James has a bad feeling about it, so he tries to secure their exit back through the window, but it has locked.
In another room the travelers scream and fall over as lightning illuminates the painting of the old woman portrait, except for Bonnie, who tells them it's only a portrait. Ash wonders if the lady pictured is the owner of the mansion, and Serena scares them all again by suggesting that the lady is already dead and a ghost, and once again she covers her mouth as she states "My mouth's got a mind of it's own today". Back in the window room, Team Rocket hear Ash and co.'s screams and James bangs on the window, trying to get out. Ash and his friends hear the knocking. Again, when Clemont tries to apply reason to the sound, saying that it must be an antique clock telling them the time, Serena wonders if it is the sound of Dracula driving a stake into someone, saying "what's with me today!?" In the portrait room, Team Rocket is frightened by the same painting of the old woman. Ash's group hears their screams and there is no denying it.
Team Rocket inches along, trying to find an exit. At the end of a hallway they're passing, they see three glowing circles of light. It is an Espurr, playing with a floating ball with its psychic powers. It sends the ball flying towards Team Rocket, who take off down the hallway in fear. Ash and his friends again hear the ruckus and are about to find an exit when they too see Espurr floating down the hallway. Bonnie runs after it,and the others have no choice but to follow her. Clemont, Ash, and Serena round a corner where Bonnie had turned only to find a dead end and no one in sight; their calls are heard by Team Rocket, who are convinced it is the dead spirits inhabiting the house. Serena, Ash, and Clemont are looking for Bonnie when Clemont lets out a yell: he has figured out that there is probably a physic Pokémon in the house. That would then explain the lights and doors shutting, and the thing that Bonnie followed was probably it. The only question was why the Pokémon wouldn't let them out.
In a room with alone with Espurr, Bonnie says hello and asks the Pokémon who it is and how it came to live in the mansion. Espurr floats the ball to Bonnie,who throws it back, and soon they are playing catch. On top of Bonnie's head, Dedenne attempts to catch the ball, but tumbles, and Bonnie falls forward to try and catch it. Before she hits the ground, Espurr uses its psychic powers to suspend her right before the floor and float her back into a standing position. Bonnie realizes that Espurr turned off the lights and shut the doors. When she asks why, Espurr leads her to a playroom, where Bonnie and Espurr play together.
Looking for Bonnie, Ash and his friends follow a sound. They burst in on Team Rocket, who are wrapped in sheets and stammering in fear as they try to deliver their speech. The travelers accuse Team Rocket of making the mysterious things occur and taking Bonnie, but Team Rocket denies it and just want to get out of the mansion. Just then, they all hear a crash above them and Team Rocket, frightened, runs off. Serena, Clemont, and Ash go and check if the sound can trace them to Bonnie. In reality, the crash was the sound of a rocking horse falling over in the playroom. Dedenne asks Espurr about the green pendant it wears, and Espurr leads them to the room with the old lady's portrait; pointing out that the pendants are the same. Ash and company hear the conversation and rush in the room and find Bonnie, who shows them Espurr. She explains Espurr has been trying to tell her something the whole time, but she doesn't get it. Team Rocket comes in and offers Meowth as a translator. Espurr tells the group that it wants to give the pendant back to the old lady because it owes a lot to her. The old lady had given Espurr food, a ball,and had played many games together. One day, the old lady gave Espurr the pendant. When Espurr returns to play, he finds the mansion empty. It asks where has the old lady gone. The others don't know, but Clemont decides to do some research. Team Rocket, however, don't have time for any of it, and decide that the best way to get rid of Espurr is to capture it.
The two send out Inkay and Pumpkaboo, Pumpkaboo ties Espurr up and drains its energy with Leech Seed, and Inkay follows up with Psybeam, straight towards Espurr, Ash, and his friends. Espurr uses Protect and stops the attack, also breaking its own bonds. It picks up Team Rocket with its psychic powers, and blasts them off, but Team Rocket are happy to have finally escaped the mansion.
In the morning, the rain has cleared and a car pulls up to the mansion. Ash and others promise to find the old lady as a woman comes into the room, asking if they meant Grandma Lacy. The woman introduces herself as Elise. She explains that Grandma Lacy has passed away (this proves one of Serena's statements from earlier as a fact), and turns away. Espurr floats the pendant over to her. Elise reveals that they have decided to destroy the mansion and that she came to do a checkup. However, meeting Espurr has changed her mind, and she decides to renovate instead. She promises to hang up the portrait of Grandma Lacy and play with Espurr, too, when she moves into the mansion. She offers to take Espurr to Grandma Lacy's grave to pay its final respects. Elise's car drives away as Ash and his friends wave goodbye. On their way to the graveyard, Elise gives the pendant back to Espurr to keep forever, and the two become fast friends.