Ash, Misty, and Brock make their way through Gringey City. The air and water there is incredibly polluted thanks to the many factories. Ash notices that Pikachu is acting weird. Sparks are coming out of its cheeks and its face is red. A shadowy Pokémon watches from a nearby alley. Ash wears rubber gloves as he rushes Pikachu to the Pokémon Center. Meowth watches them enter from a periscope deep in the sewers. Jessie and James begin to do the motto, then complain about the horrible smell instead. Meowth gives them scuba suits to wear, and says he'll stay there to pump them oxygen and fresh air. Meowth tells them to dive into the water and swim through the pipes to the Pokémon Center, but they refuse. Meowth pushes a button which delivers the hapless humans an electric shock. They reluctantly enter the sludge water of the sewers. Ash rings the bell at the desk. A Nurse Joy comes out of a nearby room, yawning. It's late at night and she dismisses Pikachu's condition as a cold. When Ash yells at her for not being very helpful, she explains that the sparks coming out of Pikachu's cheeks are an early symptom of a cold in electric rodent Pokémon. She suggests that they leave Pikachu there for the night, and it will be fine in the morning. At the same time, a large group of Grimer block the water flow into the hydroelectric power plant, causing the power to go out. This causes the power supply to Team Rocket's scuba equipment to go dead. There are also several Pokémon in the intensive care unit at the Center, and if the power is not restored soon, bad things will happen! Ash, Misty, and Brock decide to head for the power plant to try to do something. Pikachu cries out as they leave. They ask an Officer Jenny for directions, as Pikachu comes out of the nearby bushes. Misty realizes that Pikachu is afraid that they won't come back for it later, so Ash decides to let it come along. Pikachu jumps into Ash's arms and Ash gets shocked as the shadowy Pokémon watches from a nearby bush. Somehow, Meowth gets Jessie and James back on the surface level as they gasp for air. Meowth watches as Ash, Misty, and Brock race past the alley they are hiding in. The group arrives at the power plant. They enter and nobody is there to greet them. Misty looks at a map and points out the direction to the central control room. Misty gets spooked as something flies behind her. After a philosophical discussion about Misty's cowardice, both Misty and Brock spot something behind Ash. He turns around and nobody is there. The shadowy figure appears behind Pikachu. Ash looks it up on the Pokédex and it's a Magnemite, the Magnet Pokémon. Ash decides to try to catch it, but Magnemite only seems interested in Pikachu. Magnemite seems to be in love with Pikachu for some reason. Ash yells at the Magnemite to cut it out, and the Magnemite backs off. A nasty stench enters the corridor. They turn around to see a grating fall off the ceiling, followed by several Grimer. Brock decides that it would be best not to say anything to insult their pride. Ash pretends to compliment their unique smell, but Misty says it stinks, and the leader of the Grimer, a Muk, rises from behind them. With a command from Muk, the Grimer attack. Ash, Misty, Brock, and Pikachu run. As they round the corner, they run into two plant workers. The Grimer approach, and they all start running for the control room. They all hide in the control room. One of the workers explains that the Grimer are clogging the sea intake, preventing the power from coming back on. The Grimer bust down the door. Pikachu uses his Thunder Shock attack to knock out some of the Grimer, but it's not good enough. Suddenly, the Magnemite knocks out the grating above them, and several Magnemite and Magneton arrive. Their combined electric attack is enough to chase away all the Grimer. They also manage to get rid of the Grimer blocking the flow of water into the power plant, and the power is restored. However, the Muk leader remains. Pikachu uses Thunder Shock, and Pikachu's obsessed Magnemite assists with a Thunder Shock of its own. The combined electric attacks knock the Muk unconscious, and Ash catches it in a Poké Ball. To his discontent, he realizes that the smell of the Muk comes through the Poké Ball! Everyone is now outside, and the sun is back up. Pikachu seems to be a lot better now. One of the power plant workers explains that when an electric mouse builds up too much electricity, its body becomes magnetized and it seems as though it has a cold. The Magnemite is no longer interested in Pikachu. Magnemite was in love with Pikachu because it was magnetized, but Magnemite has no interest in a non-magnetized electric mouse. A Gyarados submarine comes out of the water with a large magnet attached to it. Team Rocket's plan is to use the magnet to capture Pikachu due to the fact that its body is now magnetized. What they don't know is that Pikachu is no longer magnetized. When they activate the magnet, Magnemite and Magneton from all over town are sucked onto the magnet. The weight of all the Magnemite and Magneton cause the sub to sink. As Ash and the others prepare to leave Gringey City, they mention that the Grimer horde was a sign that the town needed to be cleaned up and suggest that if the residence clean up the air and water, they'll restore the city to its former glory. Taking the advice to heart, the residence bid farewell to the kids with hopes of a brighter and greener future. Meanwhile, at Professor Oak's house, a Poké Ball arrives from Ash. As Professor Oak wonders what Ash caught this time, the Poké Ball opens up, and Professor Oak covers his nose in disgust as Muk appears.