Kid Carter and his Sidekick Mistral

Kid Carter and his Sidekick Mistral is a radio series Arthur and D.W. discover when locked inside the restaurant in the episode "Happy Anniversary." It is a western cowboy-themed adventure with characters resembling many of Arthur's friends.

Plot
The show begins by showing Kid Carter (Arthur) and Mistral (D.W.) continuing a search on horseback for the infamous Burlap Brothers. Tired and empty-handed, the two head for the nearest town in search of food and shelter from the desert. The Burlap Brothers (the Tibbles) are already there, meeting with the corrupt Mayor Mousesizzle (Mr. Ratburn), who notices Kid Carter and Mistral as they enter town. The mayor doesn't seem troubled and quickly thinks up a plan to get rid of both heroes forever.

Kid Carter and Mistral are wondering what to do with their limited money when the two disguised Burlap Brothers head outside to convince them that a nearby gold mine is a quick way to get rich. The four head out to the mine together, but the Brothers wait outside the entrance, trapping Kid Carter and Mistral inside with a giant boulder and laughing. The gold mine is actually a coal mine and, defeated, Kid Carter starts to sing a song about their troubles on his guitar. Mistral doesn't give up hope as easily, and she rips the guitar out of Kid Carter's hands ("Quit your crooning, Kid!").

Then it is Mistral's turn to panic. She begins to distress about the lack food and air in a way similar to D.W.'s panic after getting trapped inside the restaurant room. Kid Carter calms her down and then is lucky enough to find a miner's helmet that will help them find a way out. The episode ends with the discovery of some unknown amazing item, with a narrator's voice cutting in to tell listeners they have to tune in tomorrow to find out.

Arthur and D.W. are upset at the cliff-hanger ending, but become inspired to use what they learned to find a way to get out of their locked restaurant room.