As darkness falls on 10 May 1975, a little boy waits alone on the steps of an amusement park. The park is about to close and everyone is leaving, except the child. He continues to wait there, not daring to move. He has been told to stay right where he is. Only no one is coming back for him. Why has he been abandoned, with only the briefest of notes to whoever finds him?

And what connection do the events of this day have to the death of Gerda Persson 30 years later - a woman who leaves few clues to her life, apart from a freezer full of books?

Karin Alvtegen was born in Sweden and had a varied career, including work in set design for film and stage, before she started to write. She won Sweden's most prestigious crime novel award, the Glass Key, in 2000. She lives in Stockholm and is the great-niece of Astrid Lindgren (author of the Pippi Longstocking stories).

Among Sophie Ward's numerous and varied film appearances are Young Sherlock Holmes, Bela Donna and Out of Bounds. Her television roles include Dinotopia, Heartbeat and Holby City, while on stage she has been seen in One Flew Over the Cuckoo's Nest, An Ideal Husband and Nothing.