In Liverpool, on a stormy September night in 1920, two women from very different backgrounds give birth to daughters in the same house. Enemies at first, they later become friends when separate troubles unite them. But friendship between their daughters, Cara and Sybil, is a different matter. Nineteen years later, at the beginning of the Second World War, Cara and Sybil find themselves thrown together when they enlist and are both stationed in Malta. It is a time of live-changing repercussions for them both while, back home in Liverpool, the bombs rain down on a defiant city.