After her husband David Miller disappears for five years, Lily Tuner is driven to despair and nearly dies. She leaves with her younger son Ben Miller and adopted daughter Amy Miller, raising them alone while secretly battling a terminal illness. Eighteen years later, David returns as a successful businessman, remarried to Grace Walker with a daughter, Emily Miller. With only three months left to live, Lily quietly becomes the Miller family's nanny, hoping to stay close to her children without disrupting their new lives.
