This was good but not Bullet Train or The Devotion of Suspect X good. An award winning Japanese locked room murder mystery, this book is about two friends who believe they can solve a 40 year old cold case that has long stumped the police as well as amateur detectives. All the clues are there & interestingly enough, the author interjects two notes within the text urging readers to try and solve the crime before the friends do. Entertaining read.