As the group travels through what they believe to be the Safari Zone, Ash spots a Chansey and gets ready to throw a Poké Ball, but it turns out to be Ranger Jenny in a Chansey hat. She points a rifle at Ash and arrests him for Pokémon poaching. She takes the group back to the station and explains that they are in a Pokémon Preservation Area, where it is illegal to catch Pokémon. Ash tells Officer Jenny that he didn't know, so she lets them off with a warning. Almost immediately after, she sees a red dot on her radar, signaling that there are more poachers in the area.
After Ash and his friends offer their assistance, Jenny escorts the group via jeep to the signal location, where they find Team Rocket trying to capture a group of Kangaskhan. Ash looks at his Pokédex, which says the Kangaskhan charge when in danger until they feel their young are safe. Team Rocket fires a rocket, which scares all the Kangaskhan and makes them charge towards the jeep. The group manages to escape, but Team Rocket traps all of the Kangaskhan in a net. Team Rocket pulls up in a red jeep, with a box full of Poké Balls, and admire their catch. Jenny is unable to do anything, with the jeep engine now overheated because of an earlier incident. Jessie throws a Poké Ball, but it is hit by a boomerang and sent flying back at her. Suddenly, a kid begins to yell and swings in on a vine; he cuts the net with his boomerang and sets the Kangaskhan free. The boy orders the Kangaskhan to attack Team Rocket. They are quickly surrounded and receive several tail whips before the final spinning blow is dealt and they are sent blasting off. The kid jumps into the pouch of the biggest Kangaskhan, and after his command, the entire herd walks away. Ash admires the boy's ability to communicate with the Pokémon.
Suddenly, a helicopter lands and two adults come out, saying they heard a report of their missing child in the area. At Jenny's request, they all go back to the station and hear that the boy, Tommy, is living in the area. His mother explains that, five years ago, at the age of three, the family decided to take him on a globe-trotting adventure. Tommy's father decided to hold him outside the helicopter's window, and despite his wife's warning, he dropped their son into the forest below. They managed to locate Tommy's parachute, though their search for their son was in vain. Tommy's mother then states that they received a photo of a boy leading some Kangaskhan, and thought that it might be their son. Jenny instantly recognizes the boy in the photo as Tomo, the same boy who rescued the Kangaskhan from Team Rocket, and reveals that she has a directory of his details with her. Ash and his friends instantly agree to assist in the search.
Later, Ash and his friends wander in the jungle, being forced to carry Tommy's parents in a palanquin. However, they drop the palanquin after noticing an abandoned, injured infant Kangaskhan, and Brock applies a Super Potion to its wounds. However, the Super Potion stings it as it is applied; as a result, Tommy hears the infant's cries and thinks Brock is hurting it. Brock and Misty manage to dodge the flying boomerang, which instead hits Ash's cheek. Tommy confronts the group, though Misty intervenes and demands an apology. When Tommy asks Misty if she is a person or Pokémon, she punches him and says that they are people. Tommy's parents run over and talk to him, thinking he will remember them. Misty asks Tommy to remember, though he has a flashback of being lulled to sleep by the Kangaskhan herds' singing. When he claims the Kangaskhan are his family, Tommy's father smacks him with a piece of wood to jog his memory, though he only remembers his mother. His father opens his shirt, hoping Tommy remembers him, but Misty smacks him with a piece of wood and drags him away. Confused and frustrated with the revelation he has two mothers, Tommy develops a headache. Just then, Jenny's radar detects more poachers, and Tommy rushes over to the Kangaskhan to help. Seeing Tommy's knee-jerk reaction to aid the Kangaskhan, his mother feels her efforts to retrieve him are hopeless, though she is reassured by her husband.
The rest of the group find a giant robot Kangaskhan manned by Team Rocket. Jessie uses a radio speaker to pretend to be injured, persuading the other Kangaskhan to go help it. The Kangaskhan leader attempts to stop its clan, aware that something is amiss, but they ignore it and are lured in. James fires tranquilizer darts from the robot's mouth, causing the Kangaskhan to fall asleep. Tommy arrives to find most of the herd are fast asleep and responds by throwing his boomerang, though his effort is ineffective. Team Rocket turn their attention to him, launching a Rocket Punch, though Tommy dodges it. At that moment, the others arrive, and Ash calls out his Pokémon. Bulbasaur uses Vine Whip and Squirtle uses Skull Bash, but neither of them work against the robot. Team Rocket powers up for an attack, but the Kangaskhan break free. Pikachu and Charmander use Thunder Shock and Flamethrower, respectively. When Tommy throws his boomerang, it hits the robot's fuel cap and the gasoline pours out, while Charmander's fire sets it ablaze. Though the robot is on fire, it doesn't slow down and begins charging towards Jenny's jeep as she attempts to flee. Suddenly, Tommy's parents ram their helicopter into the robot in a kamikaze attack, causing it to explode. Team Rocket is sent blasting off again.
Everyone, including Tommy, fears his parents are dead and he begins to cry, but they suddenly emerge from the twisted debris, wearing similar clothes as Tommy. They reveal that they will join Tommy and his herd, much to Tommy's delight, and the family embraces each other. The next day, Ash and his friends continue on their journey, but they are worried about Tommy and his family's future. However, the Kangaskhan herd reappear on a ridge; Tommy, his parents, and the infant Kangaskhan, in the leader's pouch, wave goodbye, confirming Brock's reassurances and optimism.