As Christmas and the wedding of Dr Turner to Shelagh, the former Sister Bernadette, approach an unexploded World War Two bomb is discovered in the area, requiring the residents to be evacuated overnight to the working men's club, where the nurses take charge. Among the evacuees are young marrieds the heavily pregnant Yvonne and her husband Alan for whom the bomb recalls terrifying memories of hand to hand combat in the Korean war. He is psychologically damaged and Trixie, her own father having suffered from shell shock, empathizes. Despite opposition from the nuns she and Jenny ensure that Alan is present at his child's birth to make him feel wanted and give him confidence. Further anxiety is caused by a polio outbreak with the doctor's son Timothy among the victims but there are no fatalities and the bomb is detonated. It does however destroy the convent and new premises are found as nuns and nurses finally attend the wedding.