The film follows Keldeo, who wishes to become a member of the Swords of Justice, but before it must learn the move Secret Sword so that it can become part of the group, Keldeo wishes to fight the legendary Pokemon Kyurem, who serves as the final challenge, however the Swords of Justice refuse to let him fight Kyurem until he learns Secret Sword.
Later in the night, while the Swords of Justice are sleeping, Keldeo sneaks out to go to Full Court, when Kyurem comes out of its chamber and asks what right Keldeo has to challenge it, Keldeo lies to it and claims it is the new member of the Swords of Justice, Kyurem accepts and the two begin to battle each other. During the one-sided battle, Kyurem breaks Keldeo’s horn, causing Keldeo to become nervous and afraid. Virizion, Terrakion, and Cobalion, who had followed Keldeo, try to stop the fight which causes Kyurem to become furious. Kyurem transforms into White-Kyurem and freezes the Swords of Justice. Keldeo runs away in panic, while Kyurem starts to chase after Keldeo, announcing that their battle is not yet over.
At the train station, Ash, Iris, Cilan, Pikachu, Axew, Oshawott, Snivy, Scraggy, Emolga, and Pansage are on board the train that will take them into the city. They stop at Windy Station and purchase some Darumaka boxed lunches before they return to the train. An injured Keldeo ends up on the train and Ash and his friends find it. after it calms down, Keldeo tells them that Kyurem is following him and it is trying to escape. However, Keldeo collapses from its injuries. Kyurem arrives with its minions, several Cryogonal, still wanting to continue the fight. However, Kyurem withdraws when the train enters a tunnel. Iris remembers about Kyurem and tells them what she learned about it, having been told about it from the elder in her hometown and how it is the strongest Dragon-Type in the world