It's just a normal day for Courage, who sleeps near the hen house, where Muriel is collecting eggs. Then a masked woman comes and proceeds to whack the dog with a washbasin. When Muriel comes out from the hen house, she thinks that the woman is Courage's friend, who is playing with him. She invites her to dinner. During the dinner, the masked woman reveals herself to be "Kitty," and tells Muriel, Eustace, and Courage about her best friend Bunny, who fell in love with a gangster dog and that "all dogs are evil."
After dinner, Kitty attacks Courage again, when he is watching TV alone. Muriel sees it, but she believes that they are playing again. Muriel makes a bed for the guest in the garret. At night, Courage spies on Kitty and sees how she plays with a toy mouse, which is a reminder of Bunny (Courage does not know this). He is convinced that the Mask is evil, and tries to tell it to Muriel and Eustace, but they don't believe him. So, in an attempt to protect them both, Courage locks his owners and Kitty in their rooms, and steals the toy mouse, supposedly as evidence for the police.
Then, he drives to the Diner and learns from Charlie the Mouse that Mad Dog has Bunny in his apartment. In the meantime, Muriel, Eustace, and Kitty try to get out of their rooms. Kitty succeeds and goes to look for the stolen toy mouse, assuming that Courage stole it. Courage soon finds Bunny and saves her from Mad Dog, who gets involved in a high-speed chase. Mad Dog's car winds up driving on the railroad tracks and is eventually smashed by a powerful locomotive hauling an Amtrak passenger train.
As Courage and Bunny escape, they see Kitty on the train, who pulls Bunny up with her. As the train speeds off, the two happy friends thank Courage and admit that not all dogs are evil. In the morning, Courage returns home, and Muriel tells him that Eustace now uses the mask (which Kitty left behind at the house in her pursuit) during dangerous work.
Muriel: "Ohhhh Eustace the kitty was right about you. You can't fix a thing!"
Eustace: "Oh yeah? You want some chocolate?"
Charlie: "He and his gang live down the road. You know where. After you get Bunny out of there tell her Charlie says 'Hey'."
- First appearance of Kitty, Bunny, and Mad Dog.
- The second two-parter, after The Tower of Dr. Zalost.
- Although the train in this episode was powered by a steam locomotive, it has an air horn.
- Courage's paranoia gets the better of him in this episode. Kitty only hated him because he was a dog. She posed no threat to Muriel and Eustace at all.
- Whenever Courage thinks about Muriel and Eustace, only Eustace's lower body is shown. We see nothing above his waist. Also, during his final thought bubble, he only rescues Muriel from Kitty's mouth despite the fact that Eustace was devoured too.
- John R. Dilworth has stated in an interview that he "could not believe Cartoon Network allowed this episode to be aired" due to its strong themes of abuse, relationships, and domestic violence.
- This episode ranks among the deepest Courage episodes, with the above themes, as well as misogyny, misandry, domestic and genre violence and potentially homosexuality.
- It is possible that Bunny might be bisexual or at least Mad Dog thinks she is due to his jealousy for Kitty.
- Given the only other known cat that Courage knows is Katz, his fear of Kitty might be justified.