In Trouble (Bitter Lemon, Feb.), Ivar’s third outing for Hella Mauzer, set in the early 1950s, the Finnish PI seeks the truth about some deaths in her family’s past.

What about Cold War Finland intrigued you?

The era is fascinating, because that’s when our contemporary world took shape, really. And Finland was such an interesting place, because it had a very long border with the Soviet Union that’s very hard to monitor. I wanted the tension from that geopolitical context, which plays a big role.

What else about Finland distinguishes it from other Northern European countries?

When I started researching, I realized that Finland had one of the first female policemen in the region, Hilkka Hartamaa, but she didn’t stay in the force because there was so much misogyny. The more I read about that, the more I realized that women at the time I write about were still confined to roles that men wouldn’t do, even in such a very progressive country as Finland, which was the first country in Europe to give women the right to vote and was the first country in Europe to let women run for office. It gave me the idea to make Hella a pioneer in the Finnish police, but it’s coincidental that she also didn’t stay in the police for long. If I kept her a member of the homicide squad in Helsinki, the books would be more about relations with her colleagues, and I didn’t want that to be their focus.

Did you imagine a series when you started writing the first novel?

Well, I didn’t really start it as a series. I didn’t even see myself as a writer. What led to it was a personal tragedy. Some years ago, I lost a baby girl, who was stillborn. That was a huge heartbreak. Basically, I started writing just as a way of getting out of my head in some way. I didn’t think I’d send it to an agent or publisher, but then when I started writing, it just wrote itself. The character grew on me, and I thought there was so much else to say on Hella and her past troubles.

Why isn’t this one set in the winter like the first two books?

In summer, the nights in Helsinki are very light. Hella’s sleepless and exhausted—it’s not an easy time for her. And daylight is no shield. I wanted this contrast between a sunlit city where everything seems lovely, but some very bad things are going on. Hella’s life changed when she was a young girl when she least expected it, when her family went to buy a summer cabin, and died, not when she’d expect anything bad happening.