In the back-story of All My Sons, there's a massive crime – the shipment of airplane parts known to be defective. One partner in the firm ducks the blame. He's released on appeal and goes on to accumulate impressive wealth and prestige. The other partner rots in prison, and loses all support from his family. When the play begins, the children of these two partners suffer the repercussions of this gross injustice. One son has died, one son is morbidly depressed; the daughter and son who want to marry must fight through the tangles of their fathers' wrongs, judge them, and judge themselves.
Kate Keller is right: Ann Deever comes seeking revenge.
The suicide of Joe Keller at the end of All My Sons does not mean "justice is done." Too many people survive who were complicit in his guilt, and yet remain unpunished.