16-year-old Casey Robbins is a spirited teenage girl who loves her father Richard and stepmother Mel, and dotes on her six-year-old half brother Willie. But when she was diagnosed with leukemia, her carefree and happy life forever changed, and her only hope for cure was a bone marrow transplant. However, when Willy was proven to be a pair, Mel was reluctant to let her youngest son undergo surgery because he had a severe reaction to anesthesia during the last surgery and almost died. Mel and Richard must now decide whether it is right to risk one child's life to save another child. And Willie has the right to decide whether or not to help his hero worshipped sister...?