Based on a true story, the movie follows sisters Sandra and Beth Andersen as they grow up in a dysfunctional home with their alcoholic mother Linda. The girls become increasingly desperate to escape their chaotic home life, which includes enduring the physical and emotional abuse of their mother's boyfriends.
After their mother's latest boyfriend threatens them, Sandra and Beth come up with a plan to kill their mother by mixing a lethal dose of pills into her alcohol. The murder is made to look like an accident, and the sisters are initially successful in covering their tracks.
As suspicion surrounding their mother's death grows, however, the sisters struggle to maintain their facade and stick to their story. The investigation into Linda's death puts a strain on Sandra and Beth's relationship, as well as their relationships with friends and family members who become suspicious of the girls' involvement.
Ultimately, the sisters are caught and arrested for the murder of their mother. The film explores the complex emotions and motivations behind their actions, as well as the impact of their traumatic childhood on their decision to commit such a drastic and irreversible act.