The Cuckoo Sister treats questions of personal growth, as well as identity and isolation in a family first torn by loss, then shocked by a possible restoration. Preteen Kate Seton is faced with the sudden addition to her affluent household of a lower-class girl named Rosie, who brings with her a mystery. Either Rosie is Kate's older sister Emma, kidnapped as a baby years ago, or she is an unwanted child turned over to a wealthy family by an impoverished woman who read about the lost baby in the newspaper. The gripping story comes alive as Alcock develops it in the form of a memoir by Kate.
Kate and Rosie struggle to adjust to each other, trying to overcome not only their social differences, but also the flawed adults in their lives. The process of accepting Rosie's presence especially delivers Kate from longstanding behavioral problems which are seen to have arisen from her parents' troubles and her mother's less-than-perfect traits. Alcock conveys the thought that a happy ending may require painful adjustments and growth for a family. With sensitivity and without preaching, she ultimately affirms the healing, maturing effects of trust and love in cases of tragic loss, selfishness, and misunderstanding between social classes.
(The entire section is 204 words.)