Mildred lives for the television shows on the parlour walls. She even describes the characters on these shows as her "family." In this section of the novel, she tells Montag that she has sent in box tops and received a script. It is a new type of show in which she plays a role and essentially interacts with the actors in the show. It is a play that shows on the "wall-to-wall circuit." Currently, their parlour shows are televised on three walls. In other words, in a room of four walls, three are giant television screens. There is only one wall that is simply a wall. Mildred asks Montag to install a television on the fourth wall because this will be even more immersive and "realistic" for her to interact with the characters in the show. It would then be close to a virtual experience.
Mildred adds, "And I should think you'd consider me sometimes. If we had a fourth wall, why it'd be just like this room wasn't ours at all, but all kinds of exotic people's rooms. We could do without a few things." With a fourth wall, they would probably do without talking to each other. With each addition of a wall, Mildred gets sucked more and more into the world of television. With all four walls projecting shows, she could become completely immersed in that world. Montag objects because of the cost but he also objects because it is already difficult enough to get Mildred's attention. She is addicted to technology.