Ash, May, Brock and Max have arrived at a small town (Rinshin Town) on their way to Rustboro City. Brock decides to stock up on supplies, while Max is eager to go hunting for city dwelling Pokémon. Max soon stumbles upon a very frightened Shroomish who is hiding in an alleyway. Ash, Max, Pikachu and their new Shroomish friend head off to find a Pokémon Center. On their way they pass by a deserted mansion that is being torn down. There, the gang learns that not long ago most of the city was just plant life and that many, many Shroomish lived in the area. They also learn that strange things are going on at the mansion, and many people believe that it's haunted. A little investigation reveals that the mansion is actually inhabited by all of the Shroomish who used to live in the forest. When the forest was destroyed, they had nowhere else to go. All of the strange noises and smells that the construction workers were hearing were actually the Shroomish! The grandson of the owner decides to tear down the mansion as planned, but to convert all of that land into a forest for the Shroomish.
May, Brock, Max and Ash arrived to a small town. Max is skeptical of all the smell, but May finds it quite interesting that they arrived into a new town. The gang makes plans what to do, but first Ash proposes to get some lunch.
A group of workers are shown working near an old mansion, which find it very creepy. Among them is Team Rocket, where James and Meowth argue. Jessie is hungry, but James reminds her that they need to work to get some food to capture Ash's Pikachu.
May is loking at the dresses and jewelry, despite Brock advising to get some supplies. Meanwhile, Ash and Max have gone out of the Burger restaurant. Max then searches for Pokémon in allies and finds a Shroomish. As May and Brock are going to the Pokémon Center (while Brock carries the supplies), they hear a mention of a cursed mansion named Green Lodge. May is interested in it, and the girl answers that the workers (including Team Rocket) are tearing the trees near the mansion. The girl also says that the workers see some footprints on the floor and while they are in, they can't breathe because of the smell and get confused. Brock is terrified at the idea of going in.
Ash then scans the Shroomish. Max notices that Shroomish is angry, so he takes some of Ash's Pokémon food and offers the Shroomish. However, the Shroomish releases a the Stun Spore, making Ash and Max go away. Brock and May are shown to go to the mansion, despite Brock's fear of scary places. Ash then places some of Brock's Pokemon food. Pikachu then eats a portion of it, proving that it is delicious, so Shroomish begins to eat it.
Max notices that Shroomish usually live in forests, not in cities. Ash then advises to go to Pokémon Center, but Max places a headband upon Shroomish's head, making it really happy. Brock and May enter the mansion, while May and Ash go around it. The Shroomish then becomes sad, and walks inside the mansion, with Ash and Max following it. Team Rocket spot them and go to capture Pikachu.
The Shroomish with the headband hops inside the mansion. Ash and Max reunite with May and Brock. A man comes, warning them that the trees are being cut down. Max explains that Shroomish came into the mansion, but the man denies the fact. The man makes a flashback, saying that Shroomish lived in the town, but with the expansion of the town, trees were cut down and Shroomish disappeared, with the town deciding to destroy the mansion for more buildings to be constructed.
The gang enters the mansion looking for Shroomish. Eventually, they find it, being shivering. The other Shroomish come to it and Brock explains that Shroomish must have gotten into the mansion, with the trees being cut down. Suddenly, an explosion reccurs, revealing to be Team Rocket. James brings his Cacnea and Jessie her Seviper out. Ash declares Pikachu to use Quick Attack, but the Shroomish stop the attack by yelling.
A strange noise is coming from the mansion - hordes of Shroomish come. Jessie declares her Seviper to attack with Poison Tail, while Cacnea attacks with Pin Missile. The Shroomish use Stun Spore and the gang leaves the area. Max explains that Shroomish want to play with the man again. Team Rocket got out as well and plans to take revenge on Shroomish. Max attempts to convince the man to stop the construction, but Team Rocket appear in a machine, destroying the mansion.
Team Rocket forces the Shroomish out and grab them one by one. Pikachu uses Thunderbolt, but the machine absorbs the electricity. The Shoomish use the Stun Spore, but Brock brings Forretress to remove the spores to enter the town. Forretress uses Rapid Spin, the spores are removed. In the machine, the air is getting stale, so meowht opens the windows, but the spores enter the machine. The Shroomish use Leech Seed on Team Rocket. Max brings her Torchic and declares to attack with Ember, setting the Shroomish free.
Pikachu uses Thunder to blast Team Rocket away. After the battle, the man says the mansion has to be destroyed, but promising to plant seeds to make another forest. The episode ends with the gang leaving, waving goodbye to the man and Shroomish.
- "Look Brock. All of the latest styles. Aren't they great?
Oh yeah, gorgeous." - May and Brock.
- The Who's that Pokémon? of this episode is Snubbull.