One Small Life tells the story of Mari, a young girl who loses the only person in the world who cares for her, her grandmother, in a brutal and senseless act of violence. Because she is so traumatized that she cannot speak, she is taken to a mental institution where she is left to live out her life in darkness and despair. When Cindy, a nurse, comes to work at the hospital and starts to develop a special relationship with Mari, she begins to ask questions about the grandmother's murder and finds herself pitted against forces of evil so strong that they threaten to cost her everything she holds dear; her children, her friends and even her own life. Because Cindy and her friends are willing to give up everything that they they value in order to get to the truth and solve this mystery, they are led to realize an even greater truth - that the smallest and most insignificant of lives may be the one that is most able to save us all.