In September 1939, Nonnatus House is the beating heart of the East End community of Poplar. The nurses and nuns dedicate their lives to mothers, babies and the poor. But there is no gas and air, no penicillin, no cure for TB, and no welfare state. Then war is declared — and life gets even harder. While bombs rain from the sky, women give birth underground, families are shattered and whole streets are reduced to ruins. But courage and resilience triumphs as the community unites to survive.