The Beauty Queen of Leenane like McDonagh's other plays is about the people of Ireland and is a drama about family members. The story centers around Maureen, a spinster of 40 years who takes care of her aging and ailing mother, Mag. Mag does her best to ensure Maureen stays at home to care for her by destroying anything that has the potential to pull her daughter into the great big world she's attempted to live in and dreams to be a part of. This creates the central conflict as Mag destroys a letter from Pato that would have had Maureen join him in America. Without the letter Maureen is left to deductively reason that her mother destroyed it, and eventually leads to her torturing her mother by pouring hot oil on her, and eventually killing her.
The play centers around a line early in the play spoken by Maureen to Mag, "I'm not appreciated." This stems from years of being put off to the side and demanded to stay at home with her mother in order to ensure she is well taken care of. It is a combination of a protective action by Mag for her daughter's well-being as Maureen had a nervous breakdown 15 years previous in London, and overbearing upon the life of her child to the degree that now as a grown woman she has only one way to be heard and that is through violence. McDonagh uses violence in a way to show the extreme of pressing down the inability to fully express oneself in the environment you're raised in....eventually one is bound to explode. And, Maureen does in a fit of rage which we see her taking her mother's life.
Most poignantly Maureen's torture and murder of Mag does not solve her problem and cause her to live out her fantasy of a new life in love with Pato, but instead damns her to the same life her mother was living. This is the symbolic meaning at the end of the play when Maureen puts on her mother's sweater and sits in her rocking chair; she is taking her mother's place in the isolation of her rage. McDonagh reveals that there are generations of cruelty that has found it's way through blood into Mag and passed along to Maureen. The point is that no matter the harm a parent inflicts upon a child, choosing violence only ends in us becoming exactly like our parents and not solving a single thing that moves us forward into the freedom that we actually are seeking.