It's always exciting when new Pokémon Trainers receives their first Pokémon, but for a girl named Dawn, things will be far more exciting than she'd ever imagined! Here in the Sinnoh region, Trainers receive their Pokémon from Professor Rowan, whose lab is near Sandgem Town—but soon after Dawn leaves her home in Twinleaf Town and heads for the lab, she's hopelessly lost. Fortunately, she runs into Professor Rowan on the street and follows him to the lab. But while the Professor was out, his assistants accidentally let two of the starter Pokémon, Chimchar and Pilplup, break out of the lab.

Dawn volunteers to find the missing Pokémon and soon finds Piplup, who runs off and gets into trouble with some Ariados. Though Dawn comes to the rescue, Piplup isn't exactly grateful. Once the angered Ariados return, however, Piplup and Dawn must work together in order to escape. They end up on the shore of Lake Verity, where they spot a mysterious Pokémon. Then, back at the lab, Dawn makes their partnership official and chooses Piplup to be her companion.

Meanwhile, Ash has arrived in Sinnoh with Pikachu and his stowaway Aipom. He's ready for adventure, but not ready for trouble: Team Rocket appears and successfully steals Pikachu! But Team Rocket starts arguing and everyone ends up flying, including Pikachu. Now how will Ash and Pikachu be reunited...?