This production is thoroughly brilliant. Although it's based on a true story, it's told from the viewpoint of a delusional character, who most definitely planned and participated in the murder of her parents. Dribs and drabs of reality poke through only because of the efforts of a determined detective. We never do know exactly what happened, or why, or even if the main character's husband emotionally abandoned her.
We know the husband's brother and mother met untimely ends, and his stepmother won't speak of what happened, only to imply it was awful, and possibly the husband's fault.
The psychology of the wife, husband and stepmother is vividly portrayed, as reality takes a back seat to wishful delusions. The characters are not just likeable, but lovable, though you wouldn't want to keep them too close.