When Harriet, a working-class girl who, with her friend Mary has left her coastal job of collecting and gutting fish, stops on a bridge in her newly adopted home in York, she is approached by an upper-class gentleman. Samuel is a Quaker, a good soul, and a man interested in the new science of photography. He also collects photographs of working-class girls in their working clothes. Samuel invites the girls to come to his friends studio. While Mary is almost instantly lost to the art of photography, Harriet, a sturdier sort, goes on to get a job in the Quaker-owned Wetherbys Chocolate Factory. She soon catches the eye of a young clerk who is one of the favourites of the owners and through him discovers the deadly rivalry between the chocolate-makers.