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.

I found ‘A New Lease On Death’ (2024) and ‘Death at the Doo‘ (2025), the first two books in this series, entertaining, so I pre-ordered ‘The Key to a Killer’ and dived in as soon as the book hit my Audible library.

It didn’t disappoint, but it was a little different in tone from the first two. The relationship between Ruby and Cordelia has evolved, so that the two are more invested in each other, which meant that the plot of this book, which revolved around who killed Cordelia and why, had a bigger emotional punch than the first two.

What I liked most about the book was that I found out a lot more about Cordelia. In this book, her memory of what happened to her immediately before she was killed returns to her in tantalising drips and drabs. I liked that the memories weren’t just there as clues to solve the murder mystery, but as a means for Cordelia to reflect on the life she’d lived, how she’d acted and how she’d been treated by others. Cordelia was front and centre for most of the story, even when the details of her life were being recalled by her younger brother or her colleagues. She had a tough life and a worse death, and yet, even recalling it in detail, she remained resilient rather than self-pitying.

Ruby also continued to develop in this book; she was more confident and showed more initiative. She was no longer the nice but clueless person who first moved into Cordelia’s apartment. She’s even learnt how to keep houseplants alive.

The mystery of who killed Cordelia was twisty and well told. The solution to the mystery worked and caught me by surprise. My only criticism is that I thought the pace lagged for a while in the middle of the novel, but it was still an entertaining read.

I recommend the audiobook format of this series. The two narrators, one for Ruby and one for Cordelia, lift the prose. Click on the YouTube link below for a sample.