At Team Flare's Headquarters, Xerosic inspects Z2 before instructing a Team Flare Admin to begin irradiating it. The irradiation hits Z2 with bolts of energy, and it cries out in pain. Xerosic looks on, impressed by Z2's power.
Meanwhile, Ash and his friends arrive in Jacore Town. Squishy appears to sense Z2's pain and hops out of Bonnie's bag and scrambles onto her head. Bonnie notices that Squishy seems to be sad and sings her song to try and cheer Squishy up. Once the song is over and Squishy appears to feel better, they continue on their journey. Along the way, Serena spots an advertisement claiming that a beautiful gem is on exhibit at the hotel. Both her and Bonnie are keen to visit the exhibit. Serena suggests they do so, which they agree to do. They head off to the hotel, unaware that a mysterious figure is watching them from the rooftops. Ash and his friends arrive at the hotel, only to learn from the receptionist that the exhibit is closed. The receptionist invites them to come back another time. Ash asks if they have a room available, and since they do, he suggests staying the night and checking the exhibit tomorrow. Later that night, the mysterious figure from before opens a skylight in the roof and jumps down into the exhibit. The figure approaches the gem, which is locked, but with the assistance of Lefty, he starts to open the lock. In a nearby corridor, Serena suggests they go to bed early when an alarm sounds and they spot two guards running past, saying it's the gem exhibit. They decide to follow the guards. At the exhibit, a guard notices that the gem is still there as another notices the padlock is unlocked. They then hear laughter from the skylight and look up just as Ash and his friends arrive. The laughing figure introduces himself as Master Thief Keyes and admits to opening the lock before throwing down a calling card and escaping while the guards call for Officer Jenny.
When Officer Jenny arrives at the hotel, she questions Ash and his friends about the incident, with a Binacle "arm" observing them. Their conversation is interrupted when Ed, the locksmith who had created the lock that was supposed to be guarding the gem, reaches the crime scene. Officer Jenny reveals that Keyes always seems to only break open Ed's locks, but fails to steal any valuables, a fact which surprises Ash and his friends. Meanwhile, Team Rocket, who is also present at the scene, decides to make Keyes their apprentice, because with his ability to pick locks would make stealing Pokémon very easy for them.
Walking to their room, Clemont comments on the strangeness of what just happened, while Serena is mad that the exhibit got cancelled because of Keyes. Ash expresses interest in Keyes's identity. Suddenly, the Binacle "arm" from before runs up to the group and latches onto Bonnie's head. Ash and Clemont successfully pull it off, but it attacks the two and latches onto Bonnie's head again. Ash looks up the Pokémon in his Pokédex, and Clemont comments that Binacle usually live in pairs. Ed shows up, and the Binacle turns itself around. The locksmith confirms that the Binacle "arm", Righty, is his Pokémon, and that it had run away after a fight with him. Ed tells Righty to forget about Lefty and to come with him, but it refuses, prompting Ed to get angrily demand that it stop being stubborn. Serena tries to calm him down, and when prompted, Ed reveals that Righty has been looking for Lefty and Locke, his apprentice, since the day they left. The locksmith reveals that Locke had been unsuccessfully trying to pick a lock one evening when Ed showed him how to do it properly. Ed explained that, to open a lock, one needs to show kindness to it, just how one would show kindness when trying to get a person to open up. He added that Locke has a lot to learn about lock picking. Feeling disrespected, Locke quit his job shortly after the incident, and Lefty left with him. Ed confirms that, despite Righty's feelings for the two, he has not cared for the two at all since the day they left. He asks Righty to come with him, but Righty refuses and sticks its tongue out. Ed gets angry again, but Clemont calms him down and proposes that Righty stay with them for the night. Bonnie promises to take good care of the Two-Handed Pokémon, to which Ed concedes.
Back at his shop, Ed wonders about the lock picking incident, claiming that only he and his apprentice should be able to pick his locks. In a forest, Locke proclaims that Ed would now have to accept that the Master Thief is good at lock picking, and he thanks Lefty for its help. Their conversation is interrupted by Team Rocket when James throws a device at Locke, binding his arms. Locke explains that he does not have the gem they might be looking for, adding that he only picks locks and does not steal. The trio shrugs him off, saying that they have business with him and his Binacle instead.
When morning sets in, the group sets off to look for Locke and Lefty, but is confused on where to start looking. Clemont sees this as the perfect opportunity to introduce his Binacle Finder, claiming that once it is attached to Righty, it will find a Binacle with the same exact bio-metric data. The invention seems to work, and the group sets off on their search. At the Pokémon Center, Team Rocket forces a bound Locke to pick the door lock so that they can steal the Pokémon inside. Locke agrees, much to Lefty's shock, and asks the trio to set him free so that he can uses his hands freely for lock picking. Once free, he pretends to follow their orders, but instead has Lefty use Brick Break on Meowth. He confirms that he will never steal and runs away with his Pokémon. A displeased Jessie and James send out Gourgeist and Inkay respectively to attack with Seed Bomb and Psybeam. Dodging the attacks, Locke runs into Nurse Joy and asks her to contact Officer Jenny to tell her about the Pokémon Center thieves. However, Team Rocket catches up to them, and Team Rocket commands Inkay to use Psybeam and Gourgeist to use Seed Bomb. The attacks accidentally blow up a generator connected to the Pokémon Center, blasting them and their Pokémon off in addition to starting a fire. The group also notices the fire, and Clemont states that his device is pointing to the Pokémon Center.
A concerned Nurse Joy tries to enter the ablaze Pokémon Center, but Locke stops her, deeming it to be quite dangerous. The group reaches the Pokémon Center, and Righty gets excited when it sees Lefty. Ash explains Righty's excitement to Locke, but Locke decides that the fire is more important right now. He suggests that Nurse Joy contact the fire department while he and Lefty decide to enter the Pokémon Center and retrieve the Poké Balls containing the Center's Pokémon patients. As he sets off, the fire intensifies, so Ash sends out Greninja to use Water Shuriken and put out the fire. Bonnie has Righty use Water Gun while Ash, Serena, and Clemont manually decide to douse the fire. Squishy seems curious as Locke passes through the fire, reaches the door, and picks the lock to enter the building. Once inside, Locke and Lefty put all of the Poké Balls in a cart. The fire outside, however, moulds the structure of the lock, leaving Locke, Lefty, and the Pokémon trapped inside. Locke shouts for help, and Righty decides to go to Ed for help, carrying Bonnie alongside it. Locke tries to pick the lock open, but starts coughing due to the smoke. Ed reaches the scene, and despite a fireman's warning, decides to try to save his apprentice. Locke and Lefty, still coughing from the smoke, are contacted by Ed, and as they try to pick the lock, Locke feels apologetic and concerned about the idea of him dying in the fire. He reveals that he is indeed Master Thief Keyes, which is an alias he had assumed to gain acknowledgement from Ed. Ed, however, orders him to be quiet and just work his hands, then reveals that he knew about it all along. He further explains that only two people - himself and Locke - are able to pick the former's locks. Praising the Master Thief, Ed claims that he is a fine locksmith, something which overwhelms Locke. After some effort, the door opens. Ed, Locke, and Lefty rush off to safety, with Locke commenting that they did quite well indeed.
With the fire put out, Officer Jenny inspects the area. Ash expresses his surprise on learning that Locke was Keyes all along. Locke apologizes for his actions, and Lefty comforts him. Officer Jenny arrests Locke and expresses her desire to learn more about the story at the police station. Ed explains that the door to his shop is always open for Locke and hopes that he will come back someday. Locke thanks Ed for forgiving him as Officer Jenny takes him away in the car. Ash is glad that everything turned out well, and Serena is glad that Locke has a place to come back to. Ed says that, even though Locke has been arrested by Officer Jenny, he will be let off with only a warning, a fact confirmed by Officer Jenny herself. Ed asks Ash and his friends to keep this a secret from Locke. The group then continues on to Gloire City.