The Case of the K-9 Caper is the 54th episode of the Indigo League season.
Whilst Ash Ketchum and his friends are walking through a forest in order to get to Cinnabar Island. A Jigglypuff lurks eagerly behind them, and they are alerted to the presence of a Thief. Ash attempts to use his Pikachu to attack the thief, but Pikachu is frightened of his firearm. However, a Growlithe emerges to attack the thief, knocking the gun from his hand. No longer afraid of the thief, Pikachu manages to electrocute him into submission.
Suddenly, a herd of Growlithe rush through the forest, surrounding Ash and the others. Officer Jenny and other policeman tend to the fallen "Thief", before accusing Ash of deliberately attacking him. She reveals that he is a police officer training Growlithe in their specialised canine unit. Ash checks Growlithe's data on his Pokédex, as they commend the police upon their select choice of Pokémon. Officer Jenny states that she can control the Growlithe through a series of voice commands, displaying their effectiveness to Ash and the others.
Team Rocket eavesdrop upon the scene from a nearby tree, and James explains he has the perfect plan to capture the Growlithe for Giovanni. Back at the police station, Ash and his friends hungrily chow down upon food. Whilst eating, Ash commends the Growlithe upon their bravery, stating that they were much braver than Pikachu. However, he is reprimanded by Brock and Misty, who state that Pikachu wasn't trained for such a situation. Ash then asks Jenny whether he can train his Pikachu with the Growlithe squad, to which she allows it.
During the middle of the night, Ash and Pikachu are awoken by a whistle blown by Officer Jenny. After repeated prompting, Jenny succeeds in forcing a disgruntled Ash out of bed. In the training yard, Jenny states that Pikachu will be pitted in an obstacle course against a Growlithe. Ash reassures Pikachu, stating that he knows he will win easily. However, Jenny states that she and Ash will also be participating, much to his surprise. As the test commences, Ash and Pikachu blaze ahead, but are eventually stopped in their tracks by a low-lying net.
Growlithe and Officer Jenny take the lead, by crawling underneath the net. Ash and Pikachu follow suit, but are sidetracked when Pikachu's tail gets stuck in the net. In an attempt to escape, Pikachu electrifies the net, to Ash's disdain. While Jenny and Growlithe scale a high wall, Ash and Pikachu experience difficulties in doing so, resulting in another burst of electricity from Pikachu. After the obstacle course challenge, Ash refuses to admit defeat even after losing. Brock states that Pikachu is a strong Pokémon as it is, but Ash still insists he wants Pikachu to be as strong as possible.
Suddenly, a Growlithe-shaped bus bursts through the surrounding wall, and Team Rocket make their appearance. After reciting their motto, Team Rocket are surrounded by the Growlithe canine squad. James outlines their goal for seizing the Growlithe, in which they will use them to rob banks and steal artefacts from museums. Jenny denies that the Growlithe will ever join them, but Jessie and James put on gas masks, releasing "Oesophagus gas" from a canister marked with a picture of Gloom.
After releasing the gas, everyone begins to cough and splutter through exposure. Team Rocket then states that the Growlithe will no longer be able to use their olfactory senses. They then release helium from a separate canister, causing the unprotected individuals to get high-pitched voices. Officer Jenny attempts to use her Growlithe squad to attack Team Rocket, but due to her high-pitched voice they do not acknowledge the command. Jessie and James then change into a police uniform as a part of their plan's next phase.
Jessie then uses a synthesiser to make her voice sound like Officer Jenny's, which causes the Growlithe to place her under house arrest. As Officer Jenny is tied up, Team Rocket prepares to load the Growlithe into their van. However, Ash and the others attempt to put a stop to their plans, but are in turn stopped by the Growlithe. In order to escape their predicament, Ash attempts to use his Pokémon to fight them. He then realises that he left his Pokéballs back at the room, which Misty and Brock are also guilty of doing.
Pikachu interrupts the battle with a bolt of Thunder, as Team Rocket realises that they can capture Pikachu as well. Jessie then changes into Ash's outfit, using her synthesiser to sound just like him, telling Pikachu to enter the van. However, Pikachu sees through Jessie's trickery, as Brock explains that the ties between Ash and Pikachu cannot be broken so easily. Jessie resorts to using the Growlithe again, which are easily subdued by an electric discharge from Pikachu. The Growlithe reform but are defeated time and time again.
Pikachu then topples to the ground, having become disoriented after using too much electricity. Jigglypuff then enters the fray momentarily, singing its song without much effect before leaving. Due to the temporary window Jigglypuff created, Officer Jenny is able to break free from the ropes. She tries to persuade the Growlithe to snap out of it, as one of them grabs onto her hand. Jenny reminisces about various moments with the Growlithe, causing it to break free from Jessie's control.
The other Growlithe follow suit, snarling at Jessie and James. Despite repeated attempts to reason with the canine squad, the Growlithe are unfazed. Realizing the danger he is in, Meowth hightails it inside the van, leaving Jessie and James behind. The two of them run after the speeding Meowth, as Officer Jenny cuddles with the Growlithe. Ash realizes the error of his ways, as Officer Jenny states that she learned a valuable lesson too. Brock then plays around with the synthesiser, attempting to make Officer Jenny proclaim her love for him. Misty then calls him pathetic.
As Ash and his friends part ways with Officer Jenny, Brock leaves the synthesiser behind. Jigglypuff emerges from the undergrowth, eagerly eyeing the synthesiser.
- When Jessie uses the synthesiser to emulate Ash's voice in an attempt to fool Pikachu, the dial setting is still on Officer Jenny's and she changes it to Ash only after using it.
- This episode is noted for the depiction of firearms early on in the episode, as used by the Police officer training the Growlithe canine squad. However, unlike another episode to feature gratuitous reference to firearms, this episode was strangely allowed to air in the United States.
- The "Who's that Pokémon?" in this episode is growlithe.
- "I want my Pikachu to be the best Pokémon it can possibly be. "
Ash insisting upon the training with the Growlithe Canine Squad.