After her father's death, Emily is ill for a good while.
When she next emerges from the house, she has a short haircut and a sad, angelic look about her.
Around this time, in the summer after the death of Emily's father, Homer Barron enters the picture.
He's in town overseeing a crew of men in a project to pave the town's sidewalks.
Homer is a "Yankee" (he's from the North) and seems to be a real "life of the party" kind of guy.
Everybody in town is aware of his presence, and soon enough they start seeing him giving Emily rides in his buggy.
Some townspeople are happy she found somebody, even if he is a northerner.
But other people think she is shirking her "noblesse oblige" (the notion that wealthy people shouldn't associate with a person of lower rank) (3.3).
They think she needs family to help her, and consider contacting some obscure cousins, relatives of old lady Wyatt.
During the time these cousins are staying with Emily, when Emily is "over thirty" (3.6), she goes to the pharmacy and forces the pharmacist to give her arsenic (poison) but won't tell him why she wants it.
We'll just quote you the final lines of this section, since summary just won't do:
"When she opened the package at home there was written on the box, under the skull and bones: 'For rats'" (3.15).