When a Keldeo mysteriously lands in the human world, Cody's plans for the summer are turned on their head. Now he is thrown into a fight for his life against a terrible force that wants Keldeo captured and him dead. He and Keldeo will have to gather allies, and master powerful transformations if they're going to stop Kyurem from shrouding their worlds in a never-ending winter.

A reset gone horribly awry, Asriel has now returned to life. Eyes towards the surface, he aims to travel the Underground once more and be reunited with his family. But the game has changed since he last played, angry spirits and an old friend stalk him through the underground. Asriel will have to stay determined if he hopes to set everything right, and above all, forgive himself.