In Ireland at the time the film is set, 'fallen women' were considered sinners who needed to be redeemed. The film follows the stories of four young women - Margaret ("guilty" of being raped by her cousin), Rose (unmarried mother), Bernadette (too beautiful and coquettish) and Crispina (mentally-handicapped single mother) - who are all forced by their families or caretakers to go to the Magdalene Asylum.
The film details the disastrous lives of the four girls whilst they are inmates of the laundries, portraying their harsh daily regimen, their squalid living conditions and the oppressive nature of the Catholic faith at the time.
Each woman suffers unspeakable cruelty and violence from the fictional Mother Superior, Sister Bridget, despite her appearance and outward demeanour. She is characterized as sadistic and almost inhuman at times, as conveyed through her merciless beating of Rose in full view of Bernadette, or when she mockingly laughs at Una as she hopelessly clutches at her fallen hair locks. It is never made explicit whether Sister Bridget needlessly behaves tyrannically or if she earnestly believes her actions necessary in the eyes of God (it could also be seen as internalised misogyny).
The film also criticises the hypocrisy and corruption within the staff of the laundries, but it also intimates at the natures of the relationship between church and state in post-colonial Ireland. Sister Bridget relishes the money the business receives and it is suggested that little of it is distributed appropriately. Those who liken themselves to Mary Magdalene, who deprived herself of all pleasures of the flesh, even food and drink, eat hearty breakfasts of buttered toast and bacon while the working women subsist on oatmeal. In one particularly humiliating scene, the women are forced to stand naked in a line after taking a communal shower. The nuns then hold a "contest" on who has the most pubic hair, biggest bottom, biggest breasts and more. The corruption of the resident priest is made very clear through his fornication with Crispina.
Three of the girls are shown, to some extent, to triumph over their situation and their captors. Margaret, although she is allowed to leave by the intervention of her younger brother, does not leave the asylum without leaving her mark. When she deliberately asks Sister Bridget to step aside for her to freely pass, and being sharply shot down, Margaret falls to her knees in prayer. The Mother Superior is so surprised, she only moves past her after the Bishop tells her to come along. Bernadette and Rose finally decide to escape together, trashing Sister Bridget's study in search for the key to the asylum door and engaging her in a suspenseful confrontation. The two girls escape her clutches and are helped to return to the real world by a sympathetic relative, their story optimistically ending when they board a coach bound for the ferry to Liverpool. Crispina's end, however, is not a happy one; she spends the rest of her days in a mental institution where she dies of anorexia at age 24.
The epilogue to the film gives a brief description of the lives of four of the inmates after the girls leave the asylum by the late 1960s but according to one source these "biographical details" are fictitious. They are actually details of real women interviewed who "inspired" the characters in the film, even though the stories in the film were fictionalized and varied substantially from the true stories (for example, the real women did not all know each other, and one, not herself a Magdalene, was raised in an orphanage associated with an adjoining Magdalene laundry). It is noted that the last Magdalene asylum closed in 1996.