The Key to a Killer (The Ruby and Cordelia Mysteries, #3) by Olivia Blacke 
Series: The Ruby and Cordelia Mysteries #3
Published by Minotaur Books on October 20th 2026
Genres: Paranormal/Urban Fantasy
Pages: 368
Format: eBook
Source: Netgalley
I received this book for free from Netgalley in exchange for an honest review. This does not affect my opinion of the book or the content of my review.
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A woman and her ghost roommate investigate their most personal case yet in Olivia Blacke’s The Key to a Killer, the next book in the Anthony Award winning Ruby and Cordelia Mysteries.
When Ruby Young discovered that her Boston apartment was haunted, she did what any reasonable person would do: befriend the ghost. Their relationship overcame a shaky start—Cordelia Graves never wanted a roommate in life, she certainly didn’t want one in death. After working together to solve a few murders, the two are close friends, but there’s a lingering question neither of them have been able to answer: what led to Cordelia’s death?
Lately things have been adding up that suggest foul play. And when Cordelia’s memories of that day start to come back, the roommates can’t ignore it anymore: Cordelia was murdered. Ruby and Cordelia are going to have to piece together what Cordelia’s final days looked like—otherwise a killer could go free.
How can solving a murder be a let down?
Ruby Young and her ghostly roommate, Cordelia Graves, have worked together to solve two murders: one at their apartment building and one at their job. Now Ruby and Cordelia have finally decided it was time to solve the most important investigation–who killed Cordelia.
Ruby not only moved into Cordelia’s apartment but, with Cordelia’s prompting, Ruby took over her receptionist job at TrendCelebrate. This all leaves Ruby perfectly set up to investigate everyone in Cordelia’s life just before someone took it–because it certainly wasn’t Cordelia no matter what her death certificate might say.
It also couldn’t have been Cordelia’s little brother, Ian, who has just been released from prison. Ian now knows that his sister is haunting her old apartment so Ian has taken to breaking into the apartment looking for clues or notes that Cordelia might have left for him.
The list of suspects on their fridge keeps getting longer and each one might just have had a perfect reason to need to get rid of Cordelia. There are clues that Ruby and Cordelia have uncovered over the last year, including the mysterious man who left with a computer case the night Cordelia died. Post-mortem Cordelia was accused of selling the company’s new software to the competition. Did she, or was her computer stolen by her murderer? Cordelia was having an affair with her married boss, and she isn’t the only one. Did her lover or his other lover have anything to do with her death or was it the jealous wife?
Was it luck that Ruby and Cordelia were able to solve the other murders or will solving this one put a target on Ruby’s back? This is the most important investigation and also the most dangerous.
THOUGHTS:
I don’t generally reach for cozy mysteries but I find I like these Ruby/Cordelia mysteries. Of course when you have a ghost solving murders, one of those murders that you want them to solve is their own. Duh! I have been waiting for them to solve the big mystery of Cordelia’s death. There were a lot of possible suspects from Cordelia’s life who might have turned on her. They have been discussing each possibility and building cases against each suspect of the last few books. Each one sounding more and more plausible.
While I was reading, I couldn’t stop trying to figure out which one on their list was most likely responsible. Cordelia couldn’t remember the day of her death but as the story progressed, she got longer and longer flashes of what had happened to her that day, which in fact brought even more possible suspects for the list. I couldn’t wait to unmask the villain, answer all they how’s and why’s and solve all the mysteries surrounding her death.
So about that…after all the investigating we do find out who killed Cordelia. Was it all I hoped it would be?…No. There were still one or two unanswered questions but we do know what happened the night Cordelia died and I have to say I found that answer unsatisfying and I would be pissed to be dead over such a stupid reason. I am sad for Cordelia and even thought we now know who is responsible, she still doesn’t get to come back and continue where she left off.
I like Ruby and Cordelia. I will absolutely be checking out the next book although I think a part of me will always be sad about what happened to Cordelia.
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