Ash, Brock and Misty travel to Cinnabar Island where Ash hopes to win his Volcano Badge. They are approached by a strange character speaking only in riddles while giving them clues on how to locate the gym. Once inside the gym, Ash and Pikachu have a super hot battle with a spitfire Pokémon they've never seen before!
Ash and his friends take a boat ride towards Cinnabar Island. However, they meet Gary and his cheerleaders aboard. Gary explains that Cinnabar Island is a tourist resort, and that Trainers have not ventured to Cinnabar Island since the days of his grandfather. He adds that the island no longer has a Gym, much to Ash's frustration. The ship docks and Ash and his friends leave the ship, followed by Jigglypuff.
Once on the island, the group decides to find the Cinnabar Gym, and they eventually do with the help of a local who tells them by using a riddle, which Misty solved. However, they learn that the Gym has been abandoned. The local tells them the story of how Cinnabar Island was once a hot-spot for Trainers, but tourism took off due to the rise of hot springs resorts situated near the local volcano. The Cinnabar Island Gym Leader, Blaine, closed down his Gym due to being forced to battle tourists who had no interest in obtaining Badges. The local leaves, but not before leaving Ash a business card for the Big Riddle Inn.
Ash and his friends then decide to explore the world-famous Pokémon Lab. There, they discover that it too has been turned into a tourist trap. Finding nothing else to do, they decide to look for lodging, but find that all of the rooms at the local Pokémon Center and the hot springs resorts have been booked. As a result, they camp out. Meanwhile, Gary has found himself a room, but his room entertainment is in the form of Jigglypuff, alongside Hitmonlee and Electabuzz dressed up in costumes playing the shamisen. Realizing this, Ash and his friends flee before it could sing, leaving everyone else to fall asleep. When Brock reminds Ash of the business card, they find that it also contains directions there, but in the form of a riddle. Ash and Brock are both stumped, but Misty guesses correctly again and they locate the Big Riddle Inn because of its clock tower. The local from earlier, who runs the inn, reveals that he has a vacancy and allows the group to stay for free.
However, before they can settle in, the local receives a phone call, informing him that the Pokémon Lab, home to various Fighting-type Pokémon, is under attack from a balloon. Figuring that Team Rocket is involved, Ash and his friends arrive at the scene, and quickly dispatch the balloon with Pikachu's Thunderbolt whilst riding on Pidgeotto. As a reward for helping to save the Pokémon, the local that Blaine had built a secret Gym, in a place where firefighters couldn't win.
Later that night, as Ash and his friends mull over the riddle in the hot springs, Togepi wanders off from Misty and jumps on a Gyarados tap fixture. It unwittingly activates a secret switch that moves a boulder, exposing a cave and knocking down the hot springs' gender separation screen. After quickly getting their clothes back on, Ash and his friends explore the secret cave, and find a metal door that is hot to the touch. Beyond the door, they find Blaine's secret Gym, suspended over the Cinnabar Island volcano. The local suddenly appears, revealing himself to be Blaine, who accepts Ash's challenge.
The Gym battle begins as a three-on-three battle. Confident that the Fire-type leader will use his Fire Pokémon, Ash decides to start off with Squirtle, while Blaine counters with a Ninetales. Despite the type advantage, Squirtle's Water Gun is no match for Ninetales's Fire Spin, and Squirtle is knocked out in one shot. Deciding to fight fire with fire, Ash decides to use Charizard despite its obedience issues. In response, Blaine pulls Ninetales out for Rhydon. However, Charizard simply flies off the battlefield and naps as Rhydon is about to unleash Horn Drill. Blaine then disqualifies Charizard for leaving the ring, and Ash decides to rely on Pikachu. Pikachu's Thunderbolt does not faze Rhydon at all, but Ash decides to take advantage of using Rhydon's horn as a lightning rod, and another well-aimed Thunderbolt at the horn knocks it out.
However, Blaine isn't fazed, calling out his signature Pokémon, Magmar. Pikachu's Electric attacks do not seem to faze him, which, as Brock explains, is due to Magmar using its own body heat as a thermal lance, diffusing the electricity. Pikachu is effectively unable to attack, and Magmar's relentless Fire Punches leave it exhausted. The episode ends on a cliffhanger, with Pikachu precariously caught between facing Magmar's Fire Blast and backing into the lava below.
This is yet another episode where a real world animal is seen. While Ash and his friends are looking for a hotel to stay in, a picture of a tiger can be seen in one of the hotels. In addition, the food in Gary's hotel room consists of real world fish.
The picture in question may have been based on a similar picture that was found at Azuchi Castle, featuring a mural of a tiger among grass, making it a real-world reference as well.
Pikachu's triumph over Blaine's Rhydon in this episode has spawned the popular Pokémon internet meme "Pikachu! Aim for the horn!" The phrase is misquoted, however; the actual quote is "Pikachu, the horn!"
This episode is preceded by different episodes between the original Japanese version and dubbed versions. The episode is preceded by The Breeding Center Secret in the original Japanese version and by The Purr-fect Hero in the dub.
This episode was banned in South Korea due to its references to the Japanese culture and the overall tensions between the two countries.
When Jigglypuff sings for Gary, it sings too quickly for the music. Its lips also move too quickly.
Fire Spin is stated in this episode to be "Ninetales's most powerful attack", while just a little time later Fire Blast is called "the most powerful attack a Fire Pokémon has". Ninetales is able to learn Fire Blast so the statements contradict each other.
Misty's comment about Cinnabar Island was originally noting that Ash was coming close to achieving his goal of Pokémon Master. Brock's following comment also originally did not mention Trainers trying to learn about various techniques at the Pokémon Lab.
Gary's comment about getting a tan was originally referencing him going to the hot springs on the island. Gary also did not originally mention Professor Oak when describing how the island has fallen in popularity.
Blaine's "hotel card" was originally a pack of tissues, referencing the Japanese concept of tissue-pack marketing.
Ash's "souvenir stands" line was originally him commenting that the lab itself was another tourist trap.
The cookies that Jessie, James, and Meowth were making at their booth were originally taiyaki.
Ash's "so hungry I could eat a Horsea" line did not originally include any hyperbole.
When Ash is drawn to the hotel Gary is staying at by the smell of food, Misty originally only called to Ash to wait and did not say that they had already tried to find a room there.
The "appetizers" that Gary's troupe had was originally a delicacy called "sankai". The part where he offers to let Ash have some if he spins around three times and says "Pikachu" originally came from a play on words in the original version, based on the fact that the word "sankai" can also mean "three times".
The fourth riddle was completely different between the Japanese version and the dub:
In the Japanese version, the riddle dealt with "a lot of water above, and a lot of fire below", which also explains why Ash, Brock, and Misty were bathing at the hot springs when they discovered the Gym entrance by accident due to their deducing that the riddle had ties to the hot springs.
In the dub, it mentions a fiery place that not even a fireman can put out.
When Blaine revealed his identity in the original, he made a pun on his name, which sounds the same as the word for wig.
In the original, Ash does not tell Pikachu to aim for Rhydon's horn; his line is simply cheering Pikachu on instead.
When Blaine gives a riddle before calling Magmar, in the dub, the riddle includes a pun on Ash's name.