The episode starts off with Barry practising on Iron Island. Heracross and Empoleon destroy a rock. Empoleon gets hit by some sort of electricity which later turns out to be a low frequency sound wave. It then starts to attack Barry and Heracross. Meanwhile, Ash, Dawn and Brock are getting prepared to leave Canalave City to head to Dawn's next Contest. Before they leave, Ash receives a call from Barry asking about how his training is going. Ash tells him about his win at the Canalave Gym. Barry is at Iron Island, and something is currently wrong with his Empoleon and some other Pokémon who've begun to act violently. Nurse Joy explains that she can't figure out why this is only happening to Steel-type Pokémon.
They take a ferry and go to Iron Island but when they get to the Pokémon Center, they find out that Barry has already left. While exploring the island, the group find that all the Steel Pokémon are trying to hurt them and themselves. Suddenly, a huge Aggron comes up to them and is about to attack them when a man called Riley comes in to save the day and his Lucario gets rid of the Aggron. Lucario can use his aura to detect the waves and find out if there are any rampaging Steel Pokémon nearby, although he will not be affected because he can also use the aura to protect himself from the waves.
Team Rocket, who followed Ash and his friends to the island, have a run in with many of the rampaging Steel types before Barry and his Heracross fall onto them. He accuses them of angering the Steel types, pointing out a device he spotted in the air but Team Rocket claim it was none of their doing. He leads them to the location, which turns out to be a Team Galactic base led by Mars. They try to fight Team Galactic with their Pokémon but it doesn't work. They then fall through a crevice into a small cave with Dialga and Palkia etchings.
Ash and friends finally reach the base with Lucario's help. Eventually Mars picks up a key and inserts it into a slot into the ruins on the island and a powerful radio wave is sent out. Even Lucario can't fight the disturbance any more, and is about to attack the group. The episode concludes with Ash and Riley trying to calm Lucario down.
- Music from Lucario and the Mystery of Mew and Pikachu and Pichu are used.
- Professor Oak's Pokémon lecture: Starmie
- This is one of the few times where Carnivine does not show affection for James after being called out of its Poké Ball.
- This is the only episode featuring Team Galactic in which Saturn does not appear.
- The dub title for this episode may be a reference to the song Stealing My Peace of Mind by Rhian Benson.
- The Finnish title is a reference to a commonly used proverb.
- When Lucario comes out of control due to contact with the beam, its Aura can be seen in a dark color, which is probably a reference to the Shadow Pokémon from Pokémon Colosseum and Pokémon XD: Gale of Darkness, that also do not hesitate in attacking humans and have dark Auras, as well as to Lucario's relationship with Aura.
- The object Mars put in the ruins resembles the image from a map of Sinnoh in the Sinnoh-based Pokémon games turned sideways.
- At the scene where after Lucario gets hit by the beam, the ground's color is the same as Riley's trousers.
- The wild Skarmory were hit by Team Galactic's Golbat's Sludge Bomb despite being immune to Poison-type attacks.