Ash and Pikachu, along with their friends Iris and Cilan, are on a train headed to the next stop on their journey. From the train, Ash spots an injured Pokemon-one he's never seen before. He's trying to figure out how he can help when the train is attacked by the Legendary Kyurem, a Dragon-type Pokemon with immense power! Ash and the others barely manage to escape the rampaging Kyurem's attack, and as the dust settles, they turn their attention to the injured Pokemon. Their new acquaintance turns out to be the Mythical Pokemon Keldeo, and it's on a mission to rescue its friends-Cobalion, Terrakion, and Virizion, the Legendary Pokemon known as the Swords of Justice-from Kyurem's icy clutches! But Kyurem's rampage isn't over, and it's drawing power from Reshiram and Zekrom, changing into Black Kyurem or White Kyurem to make its attacks even stronger! Why is Kyurem attacking Ash and his friends with such unrelenting fury? How will they be able to overcome this danger? To protect its friends, to discover true power and genuine courage, and to preserve its bond with Ash and its companions, a hidden strength awakens within Keldeo…