He could see in searchlights probing the night sky, illuminating the barrage balloons which floated like giant moths above the darkened city to hinder the approach the V-2s which descended without warning like thunderclaps and which Londoners had come to fear more than any other weapon used against them. During a blackout on the streets of London on a freezing evening in late 1944, a young Polish land girl, Rosa Nowak, is suddenly and brutally killed. For the police, their resources already stretched by the new war regulations and the thriving black market, this is a shocking and seemingly random crime. No one can find any reason why someone would want to murder an innocent refugee. For the former police inspector John Madden, the crime hits close to home. Rosa was working on his farm and he feels personally responsible for not protecting her. His old colleagues Angus Sinclair and Billy Styles are still at the Yard but struggle to make sense of their few clues. Their only lead points towards Europe - but as the war rages across the continent, will they find the killer before he strikes again?