In the middle of the night, chaos breaks loose in an isolated research center as research subject RX-1, a Riolu, escapes with the help of several men and a getaway truck. But the men want to steal Riolu, not help it, so Riolu breaks out again and flees into the forest. The next day, nursing an injury, it encounters Ash and the gang, but mistakes them for more false friends and blasts Ash with Aura Sphere when he tries to help. Fortunately Kellyn, a Top Ranger from the Pokémon Rangers, catches up with Riolu. Kellyn is just in time to stop Pokémon Hunter J's minions from grabbing Riolu themselves; he uses his Vatonage Styler to recruit nearby Bug Pokémon to halt the thugs' kidnap attempt.
Now that everyone can relax, he explains that Riolu hails from the Paradise Kingdom, where it uses its special Aura powers to serve as the kingdom's guardian. Those powers strike a chord with Ash, who's able to sense mental images of Riolu's past. Riolu was kidnapped from its kingdom and is now on Pokémon Hunter J's target list, so Kellyn, together with Pokémon Ranger Solana and Officer Jenny, is here to save Riolu and get it back home. As proof of his good intentions, he brings Riolu a wooden carving made by the old man who raised it.
Hoping to evade Pokémon Hunter J, Kellyn teams up with our heroes to escort Riolu downriver toward a waiting recovery team. It's all for naught, though, as Pokémon Hunter J and her Salamence attack, forcing everyone to scatter. Ash manages to rescue Riolu and its prized carving from the water, but they wind up lost on a riverbank and cut off from the others, with Pokémon Hunter J's goons already searching the forest around them.
Ash and Riolu make a break for it, only to be spotted. Pokémon Hunter J coolly decides to flush them out into the open by burning down the forest around them, and Ash and Riolu escape the flames only to find themselves cornered by J and her Salamence. Are Ash and Riolu ever going to get out of this in one piece...?