How do Kate's memories of her daughter serve to move the plot in the novel, Ashes to Ashes?

Kate's melancholic memories of her daughter open onto the second major theme of the novel: trauma and memory. Hoag presents a number of characters who are troubled by mysterious, secret pasts. Each character's past is a mystery-within-the-mystery, and a great deal of the reader's pleasure comes from slow revelations of past events.