Writing a Mystery Novel When You Don’t Know the Ending

When I started writing Murder on Page Street, I didn’t know who the killer was. I knew someone had to die—and I knew how. The rest? It unraveled one chapter at a time.

The story is set in San Francisco, in a neighborhood I know intimately, and in a building a lot like the one I live in. It started with real places and real emotions. The foggy streets, the creaky floorboards, the sense that something’s always hiding just out of sight—it all created the mood. But the mystery itself? That came slowly. It arrived in fragments, sometimes at 5 a.m. with coffee, other times mid-flight with turbulence, or in the middle of the night when I should’ve been sleeping.

To some people, not knowing the ending might sound stressful. For me, it was thrilling. My partner and friends would ask, “So, how does it all end?” and I’d shrug. I had no idea. I was halfway through the book and still playing with different motives, different suspects, different endings. I didn’t outline much in the beginning. I just had a whiteboard on my bedroom wall—big, messy, and filled with names, notes, timelines, and ideas. I’d wake up and stare at it every day. It became my map, even when I had no idea where I was headed.

Eventually, I narrowed it down to three possible killers. Each had a different motive. One felt too evident. Another didn’t carry enough emotional weight. But the third option—the one I almost missed—unlocked something I hadn’t expected. It gave me a way to dive deeper into Frank, my protagonist. To show not just how he solved the case, but how the case broke him open. Choosing that path helped me understand who Frank really was, and why he became the man we meet on page one.

Would I ever plan everything from the beginning? Maybe. But honestly, I loved discovering the story one day at a time. It felt alive. The characters surprised me. I started liking some more than I expected, resenting others I thought I’d love, and second-guessing every single clue I planted.

Writing this way taught me to trust the process. That stories don’t always arrive fully formed—and that’s okay. The mystery wasn’t just in the pages. It was in the act of writing itself.

So if you're working on a mystery and you don’t know the ending yet—don’t panic.

Keep going. Let it surprise you.

Sometimes the best plot twists are the ones even the writer didn’t see coming.