During a train trip, Ash and friends spot an injured Pokémon they don't recognize. They're planning a rescue when the train is attacked by the Legendary Kyurem! Ash and the others manage to get the unfamiliar Pokémon to safety, and they learn its story…

The Mythical Pokémon Keldeo is on a mission to rescue its friends-Cobalion, Terrakion, and Virizion, the Swords of Justice-from Kyurem's icy clutches. But Kyurem has other ideas, and when it transforms into Black Kyurem or White Kyurem for greater power, things look grim!

Can Keldeo find the courage to stand up to this menace?