The plastic walls of a sterile room in a hospital, the home of a child who is suffering from leukaemia and has been given a bone marrow transplant & chemotherapy. The aggressive treatment of leukaemia by bone marrow transplant requires the destruction of the patient's own immune system through whole body X-ray irradiation. This is done so as to prevent the rejection of the donor bone marrow. However, the host is rendered defencless without an operational immune system (until the grafted marrow begins to function) and must be confined within a sterile environment.