Ash and his friends, training for the Pokémon League, are jogging on a cliff-side road. Ash, decked out in his white and orange shirt, is ahead of Misty (in her blue suit) and Brock (in his basketball jersey). However, Ash's progress has stopped when a truck passes by, spewing its exhaust in its wake. Blinded, Ash does not see that he is in the path of another truck heading in his direction. Misty and Brock look in horror as Ash is seemingly hit by the truck. Fortunately, the truck had swerved out of the way, leaving Ash unharmed, but it has created a large pileup behind him. Officer Jenny quickly arrives to defuse the volatile arguments caused by Ash and the drivers, who quickly speed off. As Ash wonders why the road would be so crowded, Officer Jenny tells them that it is the surfing season, and that the famous wave, Humungadunga, is coming. Surfers from all over have tried to ride the Humungadunga, which only appears once every 20 years, and plant their flag at the top of a rock, much like a famous surfer named Jan had done some 40 years ago.
Ash decides to also try surfing out, but his first go-around does not bode well. He wipes out often, and when on one occasion his foot cramps up, he is saved by an older man and his Pikachu. As Ash recovers, Misty and Brock introduce him to Victor and his Pikachu, Puka, who had help saved him from drowning. As Pikachu meets Puka outside and watch the sea together, Team Rocket, in the Gyarados submarine, plots to steal both.
In the mean time, Victor's past is revealed: 40 years ago, he had been a young surfer, who had tried to emulate Jan. Although his skills were not good, Jan eventually took him under his wing, teaching him all about surfing. After Jan had conquered Humungadunga and planted his flag atop the rock, he had given his own surfboard to Victor, simply saying "You can do it, too". With that, Jan had left to see the world. 20 years later, the Humungadunga had arrived, but he had failed. Discouraged, he was about to give up on surfing, but he then saw a Pikachu that had been cast away on a tiny raft.
This was when he first met Puka, and since then, the two have worked as a team: Puka had the ability to sense the waves, emitting a bluish glow when a big wave had approached, and it had helped the two conquer many big waves on the island—Humungadunga was the only one that they have yet to conquer.
However, Victor's reverie is interrupted by Team Rocket, who have kidnapped both Pikachu and Puka. Diving down to make their getaway (with Pikachu straining to break himself and Puka out of their glass cage), Team Rocket encounter some real Gyarados in its mating season. The Gyarados is none too pleased, attacking the submarine and finishing off with a Hyper Beam, causing the now-destroyed submarine to launch into the air and sending Team Rocket blasting off, but freeing Pikachu and Puka.
Chasing after them on a boat, Ash manages to have Bulbasaur catch Pikachu, but Puka falls into the water. Victor himself dives into the water, and using Jan's surfboard, manages to rescue Puka. However, the waves become more fierce, and Brock (now driving the boat) is forced to retreat, leaving Victor and Puka alone in the water. Just then, Puka begins to glow - a sign that Humungadunga is coming.
Ash and his friends are warned by Officer Jenny to evacuate the beach and stand as far back as possible. Worried about Victor and Puka's safety from atop a nearby cliff, they are relieved when they find Victor and Puka riding the wave. As for the two, they manage to position themselves close to the rock, and manage to plant their flag atop the rock, next to Jan's. Back on shore, as Ash congratulates Victor for achieving his lifelong goal, Victor turns to a small group of young surfers, simply saying to them what he had been told so long ago: "Hey, you can do it, too."
As the episode closes, Team Rocket is seen being surrounded by Gyarados, atop a rock with half of their submarine.