With the Sinnoh League behind them, Ash and friends take a ship back to Dawn’s hometown of Twinleaf. A crisis emerges, however, when a group of Tentacruel attack the ship and poison many of the Pokémon on board. With no other doctor on the ship, Brock is the only one who can help those Pokémon. Will he succeed before it’s too late?
Brock thinks of something and suddenly, Ash and Dawn arrive. They comment they will reach Twinleaf Town. Brock and Ash plan to get home to plan what to do next and Dawn agrees to do the same. Ash responds that when they reach the ferry, they will have to part, as he and Brock will go to Kanto. Dawn already feels sad at the thought of it, but advises them to go to her house before going to Kanto. They agree and suddenly see some small Pokémon and go to say hi to them. A woman comes and advises her Pokémon not to go alone or they will fall over. She almost falls over, but Brock gets her.
She thanks him and tells them they are from the Nursery and she takes care of them, even if they are stubborn. Brock knows for sure she needs to be honest, patient and caring for them and everything will be fine. The woman is dazzled by his response and soon finds out he wants to be a Breeder. The heroes introduce themselves, while the woman is Normajean. Team Rocket is in their submarine, going after a treasure. James soon spots something on a radar, which is guarded by a group of Tentacruel. They attempt to get them away and anger Tentacruel. James gets the treasure, which is a rare bottle cap. However, the Tentacruel attack using Poison Sting. Jessie orders James to give the bottle cap back, but James does not want to and the submarine flees. However, they hit the boat and go on it and bump into the twerps.
The heroes demand to know what have they done, but soon see Tentacruel going on the ship. They use Poison Sting, but Pikachu reflects it using Iron Tail. However, he becomes poisoned. Team Rocket flees and the Tentacruel chase them. Ash asks how is Piakchu, but Brock tells him and Dawn to go after Tentacruel while he goes to treat Pikachu. The Tentacruel begin to attack anyone, so Normajean's Pokémon protect her, but get poisoned. Pichu attempts to attack one of them, but gets attacked. The Tentacruel surround Team Rocket. Ash and Dawn come, while Brock and Pikachu also arrive. Brock sees the Tentacruel angry and suspects Team Rocket did something to stir them up. Team Rocket denies they have done anything, as James points at his bottle cap which he found among the Tentacruel. He drops the cap, Brock picks it up and goes somewhere, while Tentacruel follow him.
Brock throws the cap in the sea and the Tentacruel go towards it. Ash thanks Brock for healing Pikachu, but Brock has to treat Normajean's Pokémon, who got poisoned as well. Brock sees they have been poisoned and Pichu took things even more, as it was hit by Poison Jab. Brock would like to treat them if he had some berries, which he used to treat Pikachu. One of the boat staff comes and sees what happened. While they don't have any infirmary, but tells them to follow him to see if there are any berries among the goods being transported. They come to the room and the man says he will contact the nearest Nurse Joy for help, then goes away. Brock sends Happiny to look in the search. Happiny found a door and the heroes go inside, seeing Team Rocket eating the berries they were looking for. The heroes want the berries and Team Rocket Pikachu for them. Angered, Happiny blasts them off using Pound.
Brock sees they have only one berry. Dawn asks if the passengers have an antidote. Brock thinks it is possible, so Ash, Brock and Dawn go to look. After some time, Ash and Dawn got two berries and Brock some Healing Powder. Brock now sees it won't be enough, but an old lady comes and offers a Lava Cookie, which Brock gladly accepts to cure them all. Brock gives to them all but Pichu, who does not want to. Brock offers it to drink it instead of eating, which Pichu drinks. After some time, the Pokémon feel better, but Pichu is not feeling good. Normajean asks Brock what to do, but he is out of answers. The man comes back and tells Nurse Joy is coming on her boat. Brock contacts her and asks when is she coming. She replies it will be two hours, but Brock worries Pichu won't make it. Nurse Joy tells him he can do something else.
Dawn's Piplup uses Whirlpool and gets frozen by Buneary's Ice Beam and destroyed by Happiny's Pound. They put the ice on Pichu's head, but it still needs something else. Buizel uses Water Gun and Infernape Flamethrower to raise humidity. Pikachu shares a bit of electricity to Pichu to make it feel better for a while. Brock takes some other berries from the cargo to make a drink for Pichu to re-gain its strength. Happiny takes the drink and offers it to Pichu, but it refuses. Everyone attempts to persuade it, but fail. Happiny suddenly evolves into Chansey and learns Softboiled, making Pichu feeling better. Later, Nurse Joy treated all Pokémon. They all thank Nurse Joy, but she thanks Brock for taking a lot of care to the Pokémon. The Pokémon thank Brock and Nurse Joy recognizes some doctor talent in Brock. Dawn reminds Brock being a doctor would make him spend a lot of time with Nurse Joy. Brock flirts with Nurse Joy and Croagunk stabs him, but does not poison him.
Team Rocket is fishing on a small raft and when Meowth got a Tentacruel, they quickly go elsewhere. Brock thinks of becoming a doctor, while Ash and Dawn compliment him for such an outstanding work. Soon, they see the port and Dawn spots her mom.
- There is no Professor Oak's Pokémon Lecture at the end of this episode. Instead, a preview of the Best Wishes series featuring Snivy, Tepig, and Oshawott was shown.
- Oración, Together With the Wind, and music from Route 29 are used as the background music in this episode.
- Ash, Brock, and Dawn narrate the preview of the next episode.
- While they are looking for treasure, Team Rocket makes a reference to several main-series Pokemon games. They wonder if the treasure will be Gold, Silver, Ruby, Sapphire, Diamond, Pearl, or Platinum. James also makes a reference to the upcoming games by saying, "It's not quite that Black and White" in the dub.
- The dub's title is based on the phrase "the doctor is in".
- This episode shares some similarities with Pinch Healing!. They have a similar plot of Brock taking care of sick Pokémon that belong to a daycare worker in the absence of Nurse Joy and it is near the end of the series.
- This is the final episode where Michele Knotz voices Nurse Joy.
- Team Rocket doesn't recite the motto in this episode.
- This is the first time when the move Splash has been used in the anime by other species of Pokémon than Magikarp that doesn't use it as a result of Metronome.
- In the Hindi dub, Happiny is referred to as a male multiple times in this episode, even though it is a female-only species.
- In the Portuguese dub, Brock says that Jigglypuff's fever was gone, but it was actually an Igglybuff.
- Normajean's Teddiursa is seen using Pound despite not being able to legally learn the move in the games.
- Despite Wynaut's Ruby Version Pokédex entry claiming that it is impossible for it not to smile, Wynaut was seen not smiling at several points during this episode.