In Booker's falling stage, we see the hero fall "under the shadow" of a power that is "mysterious" and "outside" of himself. It is the hero's "immature state and limited awareness" that make him unable to battle this shadow. Similarly, by not confronting or acknowledging this shadow, Brick aids in its continued tyranny and only helps it to make it a more mysterious and powerful force.
Though made largely immobile by a broken ankle, Brick embarks upon a journey towards peacefulness through alcohol. He diligently drinks glass after glass, content to be on a quest for "the click" of peacefulness that arrives when he's had enough to drink. The family leaves him alone for a time as they fuss over Big Daddy's birthday. Brick is able to drink in peace.
The shadow or ghost of Skipper returns, having been invoked by Maggie, who believes that not talking about Skipper is like "shutting a door and locking it on a house on fire in hope of forgetting that the house is burning" (I.377-380). Brick tries to separate himself, to sever his ties to Maggie even more by urging her to take a lover, to jump off the hot tin roof of their marriage. Soon after, he retreats into the bathroom.
Maggie continues to confront the shadow when Brick comes out of the bathroom, by telling the story of how she came to understand Skipper's love for Brick. Brick becomes increasingly violent, striking at her with his crutch. Soon after, the rest of the family comes up to their room, and Brick retreats into himself, playing music and drinking.
Like Maggie, Big Daddy invokes the shadow that haunts Brick. Big Daddy uses alcohol in order to tempt Brick into explaining why he feels the need to drink. When Brick tells Big Daddy he drinks because of the mendacity in his life, Big Daddy presses on, wanting to know what Brick means by "the mendacity in his life." Eventually this talk leads to another discussion of Skipper. This time, however, Brick becomes more volatile than ever, demanding to know who told Big Daddy, who insinuated that he had had an "improper relationship" with Skipper, that he was "queer."
The more Big Daddy pries into Brick's relationship to Skipper, the angrier Brick becomes. He condemns the world for sullying a friendship that was good and pure at its heart. Finally, he tells Big Daddy he hung up on Skipper's profession of love, thus bringing on Skipper's death. Throughout, Brick is violent, throwing his glass across the room and yelling. Directly following this last confession, Brick tells Big Daddy that his spastic colon is really malignant cancer and that he is dying. In this way, the shadow passes from Brick to Big Daddy.
Brick hates Maggie. So how does Cat's ending conform to the final rebirth stage of Booker's plot analysis? Maggie saves Brick. She tells him she loves him, and she musters all of the forces and bargaining powers that she can to find a way to get pregnant by Brick. In doing so, she ensures their financial survival. We don't know whether Brick will continue to sail down the Echo Spring river, but we do know that he has, in many ways, exorcised the ghost of Skipper by unlocking and opening the doors of communication that were previously locked and bolted.