When the modest young widow Lessie Hamilton realises she is sharing her tenement landing with a prostitute, she is both shocked and upset. So when the buxom Anna McCauley begs Lessie to help disguise the fact that one of her clients has passed away in her bed, Lessie is more than reluctant to get involved. But, soft-hearted as ever, she does and, because she's desperate to buy medicine for her sick toddler, accepts the twenty shillings Anna forces on her, promising herself one day she'll pay her back.

But keeping that promise is not easy and from the day she accepts the money the fates of Lessie and her beloved younger brother Davie are inextricably intertwined with Anna's. And also with the family of her deceased client who, it turns out, is none other than Frank Warren, the prosperous sugar refinery owner whose nephew Andrew is one of the most attractive and powerful men on Clydeside.