One Song, Two Mysteries, One Killer

I've had an idea rattling around in my head for a while. It's one of those ideas that doesn't arrive fully formed. It just keeps showing up.

The basic premise was simple enough: take an ’80s song, pull a line or two from the lyrics, and build a murder mystery around it. I wasn't sure where it would go. Then I started working on The Only Key to Your Heart.

And, as sometimes happens, the idea became considerably more complicated than I originally intended.

The interesting thing about using a song lyric as the foundation for a mystery is that the lyric doesn't have to be a clue simply because the author says it is. It already carries meaning with it. Readers may recognize it. They may have memories attached to it. They may hear the melody in their heads.

Then you put that same lyric beside a murder. Suddenly, it doesn't sound quite the same.

“Let My Love Open the Door” is a perfect example. On its own, it's a familiar, almost reassuring sentiment. Romantic. Tender. Maybe even comforting.

But what happens when that phrase appears on a cassette at a staged crime scene? What happens when the same song plays during an anonymous phone call? What happens when the person using it doesn't mean what everyone else thinks it means?

That is where the idea became interesting to me. The song isn't just decoration. It becomes evidence. More importantly, it becomes a way into the killer's mind.

Calum isn't leaving clues at random. He is communicating. The songs come from his mother's soundtrack, which means every song carries something personal for him—childhood memories, grief, loss, and a history he believes was taken from him.

That changes the way the clues work. At first, investigators might see the song as nothing more than a strange calling card. Eventually, they realize it is much more personal than that. And once they understand the connection to Calum's mother and the Pulsations nightclub, the songs stop being simply mysterious. They become windows into how Calum sees the world.

That's what I like most about the concept. The song has one meaning. Calum gives it another. Those two meanings don't necessarily match. And the distance between them is where the story lives.

Even the lyric's ideas about having the “only key,” removing worry, and offering protection take on a different meaning through Calum's obsession with Zara. What might sound romantic to someone else becomes something far more disturbing when filtered through his understanding of love.

To Calum, love and control aren't necessarily opposites. They may actually be the same thing. And that gives the mystery an emotional foundation I don't think I would have gotten if I had invented a random serial-killer calling card.

But then I started thinking beyond the first book. What if the music wasn't just part of The Only Key to Your Heart? What if it became part of Calum himself? That led me to Were All Quite Sane.

In the second novel, the music becomes even more important. Calum leaves—or directs attention to—a song from his mother's era at every crime scene. And the more I thought about that, the more disturbing it became. Because Calum isn't necessarily using the songs the way a conventional killer might use a signature. He isn't simply saying, Look what I did.

To him, the music is sincere. The songs preserve a private emotional history. They connect him to his mother, his sister, and everything he believes was lost or stolen from him. The murders become part of that history in his mind—ritualized acts of memory, loss, betrayal, and family.

That contrasts with the music and the violence, especially unsettling. A tender song playing alongside a brutal crime should feel wrong. That's exactly what I want it to feel like. The music may sound comforting to everyone else. To Calum, it means something completely different.

And in “ We’re All Quite Sane, that pattern becomes recognizable. Zara recognizes the song and staging from the Pennsylvania case. Suddenly, the music isn't simply atmosphere. It confirms something she desperately hoped wasn't true. Calum has resurfaced. Even more disturbing is the fact that the music can reach Zara directly.

“Happy House” reaches her by phone. At that point, the songs stop feeling like clues left behind for investigators and start feeling like communication. Calum isn't just committing crimes. He's talking to her. That changes the relationship between them. Then there is the epigraph: “It’s safe to calm.” It's supposed to sound reassuring. Instead, it becomes threatening.

The words promise safety at precisely the moment when safety is disappearing. The reassurance becomes false, almost mocking, and that contrast fits the larger feeling I want the novel to have. Everything sounds like it should be okay. It isn't.

And that may be the thing I find most compelling about the entire concept. The music provides emotional continuity between the books. It connects Calum's present violence to his mother, his sister, and the unresolved trauma that began in the first novel. The songs become a thread running through his history, and each new song gives the reader another piece of that history.

Which means the series could continue. Different song. Different crime. Different memory. Same killer. That is a surprisingly interesting structure to me. Most murder mysteries are built around the question of who did it.

This series could eventually become something different. We know Calum. We know what he is capable of. We may even understand some of the reasons he believes he is doing what he does.

The question becomes something else: What song will he choose next? And perhaps more importantly: What does that song mean to him?

That gives the music a purpose beyond creating an ’80s atmosphere. It becomes a clue, a mood, a memory, a psychological signature, a form of communication, and a character development all at once. The strongest part of the concept may be the tension between what the song means in itself and what Calum makes it mean.

A love song can become a threat. A song about safety can become terrifying. A familiar melody can become evidence of a killer's return. And something that once represented childhood or family can become inseparably connected with murder.

I don't know yet whether The Only Key to Your Heart and Were All Quite Sane will ultimately become two books in a larger series. But I like the possibility. Because this started with a simple question: What if I took a line from an ’80s song and built a murder mystery around it?

I think I've discovered the answer. Don't just build the mystery around the song. Build the killer around it. Then let the music tell us who he is. One song. Two possible books. One killer. And apparently, quite a soundtrack.