Laura Franklin bitterly resented the arrival of her younger sister Shirley, an enchanting baby loved by all the family. But Laura's emotions towards her sister changed dramatically one night, when she vowed to protect her with all her strength and love. While Shirley longs for freedom and romance, Laura has to learn that loving can never be a one-sided affair, and the burden of her love for her sister has a dramatic effect on both their lives. Based on Agatha Christie's metaphor 'Sometimes you haven't the right currency. And then someone else has to pay…'