The quality many of the characters in this zany tale share is self-absorption, a tendency to see life solely from their own point of view.
In the story, the action takes off when the narrator's father decides to sleep in the attic so he can think. His wife, the narrator's mother, thinks this is not a good idea, because she fears the headboard of the attic bed will fall on his head and kill him in his sleep. However, the father insists on his plan.
When the narrator falls out his bed with a crash, his mother naturally assumes this sound means the headboard has fallen on and killed her husband. Meanwhile, other people staying in the house interpret the hullabaloo according to their own self-absorbed perspectives.
For instance, the narrator's nervous cousin, Briggs Beall, is staying with them. He fears he will stop breathing in the night and die. Aunt Gracie has a burglar "phobia." She is convinced that burglars have been sneaking into her house every night for forty years. She also believes she can frighten them off by throwing shoes at them.
When the mother screams because she thinks her husband has been killed, this starts a domino effect of reactions as the various people in the house interpret the screams through their own myopic lenses and panic accordingly. Briggs naturally assumes everyone is screaming because he is suffocating, while Aunt Gracie assumes a burglar invasion. Everyone reacts in their own crazy way.
The story, while comic, suggests that people should take a step back, look at the bigger picture, and not assume everything that happens is all about them.