As London goes up in flames during the Blitz, two sisters from Bermondsey find their lives changed out of all recognition. May is known to her family as the homing pigeon because of her uncanny sense of direction. She will need it when a bombing raid destroys nearly everything she holds dear. With her home in ruins, she joins the ATS and becomes a gunner girl, operating ack-ack guns. Here she finds dangerous work, new friends and rivals - and painful choices in love. Peggy, May's elder sister, is trapped in a stifling marriage to a small-time crook, who is an expert at making his wife feel inadequate. Amid the chaos of war, a route to freedom suddenly beckons and along with it, new and passionate love. But Peggy's husband is not about to let her go easily. From the melting pot of war will come hardship and tragedy, as well as new, unexpected friendships and love affairs.