As the unfamiliar terrain of the Hebrides stretches the team to the utmost at Christmas, their return to Poplar sees them braving a landscape that feels suddenly unfamiliar. Budgets are being cut, and hospitals reorganised. Terraced houses are being demolished, and traditional family structures torn apart. There are wrecking balls everywhere, and it's up to Sister Julienne, and the midwives and medics of Nonnatus House, to help find a way out of the rubble. When they themselves come under threat, their job becomes even harder.