Pinky and Brain are genetically enhanced laboratory mice who reside in a cage in the Acme Labs research facility. In each episode, Brain devises a new plan for the two mice (led by Brain) to take over the world, which ultimately ends in failure. In common with many other Animaniacs shorts, many episodes are in some way a parody of something else, usually a film or novel. The cartoon's tagline is:
Pinky: "Gee Brain, what do you want to do tonight?"
The Brain: "The same thing we do every night, Pinky-try to take over the world."