Still on their way to Goldenrod City, Ash and co. decide to have a lunch break. Only to find that Ash's backpack had been stolen. Elsewhere Team Rocket steals a ham from Nurse Joy's grocery bag, onlt to have it stolen by something else. Brock comes up with a plan to lure out the thieves. Later that night, the thieves turn out to be the Dark Pokémon, Houndour. A Houndour with a scar on its right eye appears on a ledge. This particular Houndour is the leader of the pack. Why would Houndour want to steal food?
This episode is the only one where Pikachu uses Leer.
This episode also introduces a new Type of Pokémon in the anime: Dark Type Pokémon.
Ash says that his badges, PokeBalls and Pokedex were in his bag and all his "important stuff" were in his pockets as always. Yet, it is his badges, PokeBalls and Pokedex that he has always been shown to keep on his person (on the inside of his jacket, on his belt and in his pocket respectively).
The "Who's that Pokémon?" in this episode is Hitmontop.