Detective Inspector Gemma James and her family are back in their Notting Hill house when Gemma receives a plea for help from her neighbour, Erika Rosenthal. Erika has never shared much of her past, other than telling Gemma that she and her husband came to London before the war as refugees from Nazi Germany. Her long-dead husband was a historian and was found murdered. His murder was never solved. But now the elderly woman needs Gemma's help. It's a cold case and one that Gemma has neither the time nor the resources to investigate. But then a tragic death places the investigation firmly in the present - and into the hands of her partner Duncan Kincaid. Determined to exact justice both Gemma and Duncan hunt down a chilling killer in a case that will have lasting repercussions for everyone involved...