The main character, Scott, is a struggling writer living in California who has always dreamed of moving to Paris. However, his plans are put on hold after the sudden death of his estranged father. Upon returning home for the funeral, Scott is confronted with the reality of his sister Cindy's severe mental illness. She has been living alone in their childhood home and struggling to take care of herself.
With no one else to turn to, Scott takes temporary guardianship of Cindy and brings her back to his apartment in LA. However, Cindy's erratic behavior and emotional outbursts begin to take a toll on Scott's personal life, including his relationship with his girlfriend and his ability to focus on his writing.
As Scott tries to navigate his own grief and his sister's mental illness, he also has to contend with their complicated family history and the pain that has been passed down through generations. Along the way, he discovers unexpected compassion and strength within himself as he strives to support his sister and find a way forward for their family.
Broken Diamonds is a poignant and deeply personal exploration of mental illness, grief, and the complexities of familial relationships. It stars Ben Platt as Scott and Lola Kirke as Cindy.