A mysterious woman tries to help her son's foster family without revealing her true identity.

In a small Indiana town in 1919, Paul Ward, a science instructor, is trying to invent something that will make enough money to provide his wife Marcia, daughter Sally and a new baby with some luxuries. Into this household wanders Hannah Parmalee, who obtains a job as the family cook and housekeeper. Hannah believes in the Christian philosophy that advises an injured person to turn the other cheek. Peter Trimble, one of the boys who attends the school where Paul teaches, is the son of the richest man in town. He is also a whiz at science, and after Hannah suggests that Paul set a good example for the boy, he asks Peter to help him. Sally develops a schoolgirl's crush on Peter. Together Paul and Peter perfect an iceless icebox. Peter accidentally lets the town mechanics, Joe and Bill Ellis, see the invention, and after the brothers steal it, they patent it. Peter feels so bad about this that he lies when Paul asks him about it. In the meantime, Sally develops pneumonia. Hannah persuades Paul to give Peter another chance and he develops a new and better feature for the icebox. Sally recovers and leaves on a trip with Marcia and the baby. Hannah faces her own crisis when Thomas Bradford, a wealthy Chicagoan, visits to discuss financing the invention. She reveals to Paul that Peter is her son and Bradford is his father. An unwed mother, she was forced to give up the baby, and Sam Trimble adopted him after his own baby died. When Bradford learns that Peter is his son, he wants to claim him, but Hannah persuades him to leave Peter where he is. Soon after, she leaves the Wards, and is secure in the knowledge that Peter is in good hands.