Rex is the family bull terrier who sleeps in the hallway between bedrooms.

The scenario is as follows. The narrator's cousin, Briggs Beall, is visiting the family at their home in Columbus, Ohio. Briggs, who is a very nervous person, has a great fear that he will stop breathing while he is asleep at night.

Briggs is sharing a bedroom with the narrator. Meanwhile, the family's father has decided to sleep in the attic so that he can think. The mother is worried the heavy headboard from the attic bed will fall on her husband and kill him in the night.

When the narrator's cot, which he is sleeping on so that Briggs can have his bed, collapses, the mother thinks it is the headboard falling on her husband. This causes a comic chain reaction of commotion in the house that includes Briggs waking up and breaking a window because he thinks he cannot breathe.

We learn that Rex, who starts barking, blames the chaos on Briggs because he doesn't like Briggs. The story explains:

The dog, who never did like Briggs, jumped for him—assuming that he was the culprit in whatever was going on.

We never learn, however, why Rex does not like this cousin.

The story offers a humorous glimpse of what life was like in the United States in the the 1930s in a middle-class home.