How does Priestley present guilt in An Inspector Calls?

In this play, Inspector Goole arrives at the Birling home with news of a young woman who committed suicide by drinking disinfectant. Priestley establishes guilt by showing how each family contributed to her hardships until the young woman killed herself. None of them directly poured the disinfectant down her throat, but each one put a nail in her coffin, so to speak, through the way they treated her.

It emerges that the woman, whose name changes to reflect how the different characters knew her, worked in Mr. Birling's factory but was fired for asking for a small wage increase. Fortunately, she was able to find a new job in a department store, but she was fired when Sheila, the Birlings' adult daughter, complained about her and demanded she be fired. This sent the woman on a downward spiral. She finally had an affair with Gerald Croft, Sheila's fiancé, to keep herself afloat; she was then impregnated by Eric Birling, Sheila's brother. Abandoned by him, she went for help to a charitable committee headed by Mrs. Birling. Mrs. Birling turned down her request on the theory that the baby's father, whose name the young woman wouldn't reveal, should be held responsible.

The play shows that the wealthy Birling family and Gerald Croft used their wealth and power to oppress this young woman without money or status. They are all implicated in her death.

How does Priestley create tension in An Inspector Calls?

Priestley creates tension by making the play a mystery which unravels slowly, entangling the Birling family members.

Strangely, the Inspector is unknown to Mr. Birling, who is familiar with the police. Purposely, Inspector Goole only questions one person at a time because, as he says,

"...what happened to her may have determined what happened to her afterwards, and what happened to her afterwards may have driven her to suicide."

It seems that each person in the Birling house plays a role in the death of Eva Smith, and no one sees her photograph until the Inspector allows him or her to do so. The Inspector speaks first to Mr. Birling, who fired Eva after she went on strike for higher wages; then the Inspector talks to Birling's daughter, Sheila, who in jealousy had the young woman dismissed from a dress shop. The young woman then changed her name and tried to have men take care of her; soon, she met Gerald, Sheila's fiance, who put her up in a friend's apartment and became her lover.

When she hears Gerald relate what has happened, Sheila says  to him,  

"Why—you fool—he [the Inspector] knows! ...And I hate to think how much he knows that we don't know yet. You'll see, you'll see....We all started so confidently until he started asking questions."

Tension becomes so great between Sheila and Gerald that Sheila returns the engagement ring to Gerald, telling him, "You and I aren't the same people who sat down to dinner."

Of course, the greatest tension is created among the family members when they learn that the cold-hearted Mrs. Birling refused Eva Smith the aid of her Brumley Women's Charity Organization. When Eric learns that Eva was refused, he blames his mother for Eva's death as well as the death of the baby—"your grandchild," he tells her. Sheila, too, is upset with the mother.

Clearly, the family members are equally guilty of the girl's demise as they have each acted selfishly and even arrogantly. The greatest irony, however, is that they discover what types of persons they all are behind their veneers of respectability.