Ash and friends return to New Bark Town, but before Ash is able to register for the Johto League Championship, Professor Elm sends him on an errand to retrieve a Pokémon egg from a nearby marine Pokémon laboratory. At the laboratory, Ash and his friends meet up a young researcher whose in a hurry and uses supersonic waves from a Lanturn and detect the singing voices of traveling Lapras. Ash meets up with his old buddy, his Lapras, the one he caught at the Orange Islands. Its revealed that the young researcher's name was Naomi and that she was studying Lapras Migration routes and is the director of the Pokémon Marine Laboratory. Naomi also mention that Professor Elm told her that Ash will be coming and will retrieve the Pokémon Egg, that's why she know Ash's name. Ash ask Naomi if she spend all her time studying at about Lapras Migration, Naomi answers yes and been studying the Pokémon Marine Biology, a study of the living patterns of marine Pokémon, she also said that this knowledge improve human life too. Naomi discuss about Lapras migration and why they can navigate so quickly, Naomi says that they somehow be able to know from a great distance away when the water temperature and season is perfect for them to return then they share this information from the other Lapras but with an outstanding speed. And she figured out that the key of solving it is in Lapras' voice, then Naomi plays the traveling song that Lapras sing when they travel and they figure out that supersonic attacks can actually pinpoint their location. But Team Rocket plans to capture the whole herd of Lapras so they can rent them out with Pikachu. Naomi shows and explains the egg's history and how Naomi got it. Meanwhile, Lapras invite Ash to play with him, Misty says that's because Lapras missed Ash alot and its been a long time since they saw each other.
Ash and Pikachu was shown riding at Lapras and seem to enjoy the moment with his old buddy.
But they suddenly hear a cry of a Lapras, it is revealed that the whole herd of Lapras was caught in a net, caused by Team Rocket. When Ash and Lapras arrived as well as Misty, Brock and Naomi, James sends out Weezing, Ash told Lapras to use Ice Beam but James told his Weezing to use SmokeScreen first. Team Rocket then managed to escape with the herd, Luckily, because of Lapras ability to locate the other Lapras, they can follow Team Rocket, Misty and the others follow by using a submarine. Team Rocket uses their secret weapon to boost their speed, leaving Ash and the other behind. Misty calls Ash to transport to their submarine and follow Lapras underwater. Team Rocket was relieved that they have escaped Ash and the others, but suddenly something strike their Gyarados submarine and saw the herd of Lapras working together to escape from the net. A Lapras managed to break the net and released them one by one. Shocked, Team Rocket strive to get to the surface before the other Lapras can escape, Before doing so, Team Rocket notices that a bunch of cyclone ahead, only two Lapras are remaining in the net but before they can escape, they're caught up in the cyclone along with the submarine. Ash's Lapras locate the herd and they follow Lapras, As Ash's Lapras shouts underwater to signal the others that the help is coming and the herd managed to hear Lapras' voice, when Lapras heard the herd's reply, Lapras was relieved. Suddenly Ash and company along with Naomi notices that a couple of Lapras was missing, Brock worries that the two missing Lapras might be caught in the cyclone, Ash's Lapras tells the herd to follow that it might know something but Naomi doesn't detect anything within the radar's range. The herd communicate with each other to guide their movement and fight the strong current, the herd signals the two , but Naomi suddenly got something on her radar, the two missing Lapras was singing the herd's travel song, so the herd, managed to locate the two, Naomi said that they can distinguish the wordings of their song even there is so much background noise, they can hear the songs of their friends from miles away that the radars cannot detect, Naomi also notices that they are headed for a nearby island. In the Island, Team Rocket was exhausted but still have the two Lapras in the net. The herd suddenly appears came out of the water and Naomi's submarine also appears but before they can retrieve the two missing Lapras, Jessie and James sends out Arbok and Weezing and Brock manages to send out Crobat to battle against Team Rocket, Brock orders Crobat to use SonicBoom which hits Weezing and Arbok. As Naomi and Misty strives to release the two, before doing so, Meowth stops them but Ash tells Pikachu to use Quick Attack at Meowth. Ash, Misty and Naomi releases the two so Lapras and its mom was happy to be reunited again. Arbok and Weezing was ready to attack but stopped by the herd, the herd of Lapras, along with its Leader, used Ice Beam in order to freeze Team Rocket's Pokémon. Ash commands Pikachu to use Thunder to blast Team Rocket off. The herd of Lapras are now safe.
At the end of the episode, Ash and his friends was proud of Lapras, the leader of the herd ask Lapras to take over the lead and Naomi explains that the leader was so impressed by Ash's Lapras and decide to "handover" its leadership duty. Ash and his Lapras say goodbye to each other then the herd now set off to travel. Naomi gives Ash the egg, Professor Elm ask to bring the egg at his lab as soon as he possibly can, Ash and his friends now say goodbye to Naomi and his Lanturn. And so with the Pokémon egg safely at hand and his memories of Lapras on their mind, our heroes continue their journey to Professor Elm's lab in New Bark Town and in Johto League.
