Once again, Young has created another fantastic addition to his Müller series. This time it focuses on an abandoned scientific project and several young missing/dead boys. This book blew my mind for several reasons, the first being the twisted nature of Karin's seemingly normal boyfriend - Stasi! I certainly didn't see that coming! When i thought i couldn't be more shocked, we get thrown some hints that someone close (perhaps an old forgotten husband from the first instalment, Stasi Child) is still alive, and is about to be used to spy on Karin. This makes me incredibly excited to move onto the next book. I loved the idea that the missing boy was the son of a member of her own team, the desire in Karin to get to the end of the case only draws you deeper into the novel. I read this pretty quickly, i genuinely could not put it down. I would definitely recommend this to any lover of historical fiction!