"Cuckoo Song" is a novel written by Frances Hardinge, published in 2015. The story follows a young girl named Triss who wakes up after an accident to find that she is not quite herself. As she navigates her new reality, she discovers dark secrets about her family and the world around her. Set in post-World War I England, the book blends elements of fantasy and horror. It explores themes of identity, family, and the consequences of choices. The narrative is rich with symbolism and features a unique take on the concept of fairy tales and mythology.