Hanging Millstone tells the story of Rebecca and her husband Daniel, who are struggling to conceive a child. They decide to seek the help of a fertility clinic and end up having a baby through IVF. However, their joy soon turns to despair when they discover that their child has a rare genetic disorder that causes severe disability and is untreatable. Despite this, they love their child and do their best to care for her.
Years later, their daughter is a teenager and they face new challenges when Rebecca's estranged sister shows up and reveals a shocking secret about the IVF process that led to their daughter's birth. The revelation causes a rift in the family and raises difficult moral and ethical questions. Meanwhile, Rebecca's daughter is also struggling to find her place in the world and deal with the limitations imposed by her disability.
As the family grapples with these issues, they are forced to confront the consequences of their choices and the impact they have had on each other and future generations. The film explores themes of family, identity, responsibility, and the complex choices we make in life that can have far-reaching effects.