The Key to a Killer is book 3 in Olivia Blacke’s The Ruby and Cordelia Mysteries, but it is easily read as a standalone novel.
In The Key to a Killer, Ruby and her ghostly roommate ,Cordelia, turn their attention to Cordelia’s death which was ruled to be a suicide, but Cordelia insists she was murdered, only she can’t remember what happened on the day of her death or leading up to it.
The story is told in alternating points of view, from the perspectives of Ruby and Cordelia. Occasionally, it can be confusing when you first start the next chapter, but for the most part it’s done well and it keeps the story interesting.
I read the second book in this series and it had left me with a number of questions, and some curiosity over some of the characters in that book. I’m happy to say that many of my questions were answered, and I got to know some of the characters better in book three. I especially grew to like Cordelia’s younger brother, Ian, who appeared to be a bit of a troublemaker, and ne’er-do-well.
Like the previous book there was quite a large cast of characters to eliminate as suspects, and a number of motives to complicate things as well. This combination kept me guessing well into the book, and all of the characters and motives felt plausible. There were several times when I thought I had worked out the mystery of Cordelia’s death, but I didn’t get it right until right before the truth was revealed.
The only thing that still bothered me about this series, not just this particular book, was how Cordelia communicated with Ruby. She doesn’t appear to have an issue interacting with items in the real world so I still don’t understand why she can’t use a pen and paper instead of refrigerator magnets for communicating. Maybe it was explained in book one and I just missed it.
I enjoyed The Key to a Killer. I think most people who enjoy cozy mysteries will enjoy it, especially if you enjoy a mystery with a paranormal twist.
I received an advance review copy for free, and I am leaving this review voluntarily.
The Key to a Killer will release on October 20 2026.
