Ash and the gang are on their way to Lily Of The Valley Island and the Sinnoh League via ferry when they meet a treasure hunter named Buck, along with his Baltoy. Armed with a pirate map--and Baltoy's knack for finding hidden treasure--Buck is trying to track down a magnificent fortune. Buck asks Ash and the rest of our heroes if they will come along to help and they excitedly agree.
Buck's map guides the treasure hunters to Dandelion Island where they soon discover that the mysterious pictures of Pokemon on the map were actually a warning about all the Pokemon guarding the treasure! The Pokemon put up a mighty struggle, and at the same time, Team Rocket, armed with a copy of the same map, are on their way to get the treasure first. Fortunately, our heroes' superior skills defeat the guardian Pokemon and send Team Rocket blasting off again.
When Buck, Ash and the crew finally find the ruins where the treasure is located, they discover a powerful Claydol protecting it. Buck's Baltoy is too fast for the larger Pokemon and Buck manages to catch Claydol for his own!
When the treasure is discovered, our heroes are dismayed to find that it's just some old pots instead of gold and silver. But Buck explains joyfully that he wants to become an archeology professor when he grows up and this is exactly what he hoped the treasure would be!
And so, thanking our heroes for all their help, Buck heads off on another treasure hunt. Ash and friends resume their journey toward the Sinnoh League!