At St Agnes Hospital in Melbourne, Australia, the night staff are taking over duty from the tired day staff. Sister Frances Rankin is in love with the sensitive Dr Clayton, while his pretty wife, Leila - almost a psycopathic case - from whom he is seperated, is a patient in Frances' ward and complains of ill-treatment there. Nurse Ruth Sinclair, a determined country girl who has laid her whole future on becoming a nurse, is nervous as she is within a few days of completing her training. Alan Keene, a patient whose ribs have been broken in a motor accident, a spoilt but likable young man, falls seriously ill and Dr Clayton is called in. Leila Clayton hears of his arrival and, coming out of her ward, asks him to take her back; her plea seems so pathetic that he is forced to give a promise that he will - and his future with Frances seems doomed. A blood transfusion is needed in an attempt to save Keene's life and because of the rare type, Ruth Sinclair offers to give it, knowing well it is against hospital orders. Keene's life is not saved and in the morning Sinclair expects dismissal from the Matron who, she thinks, hates her, but instead Matron congratulates her for putting the welfare of the patients before her obsession for efficiency; astounded and happy, Sinclair hears that she is to be taken on the permanent staff. Leila Clayton learns of Keene's death from Sinclair and immediately in the distorted imaginings of her mind she thinks they have killed him. The shock brings on a fit of hysteria, which confirms once and for all her mental trouble. She is to be sent home and thus Dr Clayton is released from his promise - and from her. As the day Sister comes on duty Sister Frances reports, just a - quiet night.