After winning his fifth badge, Ash and friends begin heading for Mistralton City. On the way they notice a Joltik has taken all of Pikachu, Emolga, and Stunfisk's electric energy, leaving them severely weak. Upon healing them at the Pokémon center they run into Bianca who had the battery in her Xtransceiver drained as well. Nurse Joy determines that something must have happened in Chargestone Cave to make the Joltik and Galvantula appear in the forest. Bianca, who was already heading for the cave to see Professor Juniper, joins the group as they try to figure out what is happening at the cave.