Many years ago, I reviewed Craig Nova’s The Good Son for The New York Times Book Review, which led to a correspondence, and our friendship, which continues to this day. I wrote that the novel "has characters of great, outward bravery and of heartbreaking inner need"; I said that his characters were "as vivid with suffering and with spirit as recurring dreams." Well, that hasn't changed, but I might have also noticed—as I do now—that Nova’s characters are not easy to like; yet, in novel after novel, he made the most unlikely characters sympathetic—and, especially lately, he’s often put them on a collision course. Maybe this first and most forcefully got my attention in Tornado Alley but it continues.

So, let’s talk about collisions. What are the collisions here, in The Informer? How is it that unlikely characters become sympathetic?

I sometimes think we imaginative fiction writers are howling like lost coyotes in a wilderness of memoirists.

Craig Nova: I like the sense that one character is going to have a train wreck with another. This is more intriguing if the author makes a partnership with the reader, so the two of them together can see it coming. It is a sort of elbow in the ribs, a wink, between author and reader that makes for fun, although it is often an ominous, scary kind of fun.

And as far as unlikely characters being sympathetic, I’ve noticed that the most important thing about characters is that they want something decent, like love. And the more difficult it is to get something like love (because of unusual or trying circumstances), and the more characters want it, the more we can feel their needs. And these are human, basic needs.

In The Informer, the collisions are between two women, one from the streets and one a polite woman who works for Inspectorate A, the serious crimes section of the Berlin Police Department in 1930, and the things that are lurking in the shadows. These are events and people that these two women discover as the book goes along, but the dangers are not immediately obvious.

JI: I’ve noticed that you are having more fun with suspense in your recent books. You've always loved the ominous in fiction, those foreboding moments, haven't you?

CN: I think both of us have liked the ominous. In my case, I realized that when I wanted to relax, I would gravitate to the novels of Graham Greene, and one day I said, What tugs with such force here? And, of course, Greene never forgets the reader and is always pulling the reader along with the basics: suspense and character, and that wonderful place where they exist together.

JI: This book is set in Berlin in 1930. Why, would you do that today? Was it the desperation of the time? The more into the novel I read, the more it strangely resembled the desperation of our time.

CN: I have done a lot of reading about Berlin in the late '20s and early '30s before the darkness descended. People knew that something was drastically wrong, but they didn’t really know what to do. It is this sense of uneasiness that makes me think of our times being similar to Berlin in 1930. In Berlin there were groups who were simply believers. Turn on talk radio some evening, and you will hear the same thing. To be as precise as I can, here are the qualities in Berlin that seem similar to today: a prevalence of misinformation designed to further personal and political goals; a deep and drastic hyper-polarization of political views; an overtly hedonistic culture, where sex and celebrity reign; an unstable economy in which trust has been lost; and, a fascination with the most heinous and violent of crimes.

But this is all in the background. I am really interested in story, in how Graham Greene might have set a book here. A sort of Brighton Rock in Berlin in 1930.

JI: I’ve noticed you like to write about sex, but you don’t do so in the usual way. Can you talk about how you do this, not the sex, but the writing about it? No matter how I write about it, there's always some self-appointed person in the Good Taste Police who doesn't like it.

CN: I wonder if The World According to Garp was ever banned because of the dialogue in the beginning, in which a character says, “Semen? Did you say semen? How dare you say semen in this house…” Or something to that effect. This seems to sum up perfectly the attitude of the Sex Police.

I think that it is a good idea to set things up so that the reader imagines what is going on, but the trick, if you can put it this way, is to hint at it. I find that when people have sex in the midst of danger, the danger seems to enhance a sense of the erotic.

JI: You seem undaunted by the prospect of being in anyone's point of view—man or woman; it doesn't seem to matter.

CN: No, it doesn’t matter to me at all. I assume, no matter if characters are men or women, that they need the same basics: love, respect, some control over their lives, and that they are often afraid and that they need and look for help, which they often don’t get.

I think it is critical that a writer finds a way to love the characters he or she produces. Even the wicked and vile ones.

JI: Most writers, at least as far as I can tell, often have a special affinity with a character in a book. Do you have one here?

CN: Yes, Gaelle. Gaelle is a Gravelstone, a prostitute with an erotically appealing scar. I have always felt scarred in some way, and when I came to her, I felt a profound recognition in her scar.

I like to think of this as the ideal attitude for a novelist, to feel marked, or in some way outside regular society. This makes the novelist naturally sympathetic to the cast out, the brutalized, the screwed over.

JI: You do research to learn more about the book you are writing. What do you get? And what did you do for this book, that is one set in Berlin?

CN: Details. For instance, I once spent some time with the New York City Vice Squad (Manhattan, Morals South was the precinct). I was interested in women who had to dress up as prostitutes on Eighth Avenue. It was humiliating and the women hated it. But these women were up to far more important things. I met a police woman in the Port Authority Bus Terminal who was trying to catch a pimp. This pimp was providing child prostitutes, under the age of 14, to his customers.

I went to Berlin to see the landscape, the buildings that were still there and to talk to people. I spent time in the Berlin Police Museum with the woman who ran it. It was a way of establishing a sense of place, as much as possible.

JI: I sometimes think we imaginative fiction writers are howling like lost coyotes in a wilderness of memoirists. We often talk about how the imagination is a better tool for a novelist than experience. Why do you think this is true?

CN: The difference between the merely recounted and the made up is the difference between the mundane and the infinite. The novelist has no limits, nothing that stops a book from becoming as large and compelling and as new and fresh as he or she can make it.

JI: Let’s talk about the story of The Informer. Can you describe what is going on? What is the source of the tension in the book?

CN: It is about a polite, attractive woman, who works in the Berlin police department. Armina Treffen. She is assigned the cases, and there are many of them, where women are being killed in Berlin. Mostly these are young women who work as prostitutes near the main park in Berlin, the Tiergarten. The crimes look like copy-cat killings, but Armina suspects there is a political connection.

Armina’s investigation leads her to another character in the book, Gaelle, the Gravelstone. Gaelle is especially intriguing because her face is scarred in such a way as to suggest that her beauty is just submerged in the scar and is almost able to appear. Gaelle sells information she picks up to the various political groups in the city, both the left and the right, and she is afraid they are going to take their revenge. She is suspicious of the police, and initially resists Armina’s offer of help.

In addition to the young women who have been left in the park, a bureaucrat in the Soviet Embassy has been murdered. The precinct where Armina works is evenly divided, at least politically, and both the left-wing cops and the right-wing cops decide that it’s a good idea just to leave this murder alone.

Armina doesn’t agree. And, when things are most tense, she meets a man who seems to understand her perfectly, and with whom she is willing to take a chance.

JI: What scares you the most in writing a book? Frankly, I'm scared all the time!

CN: I’m always afraid the book won’t work out and of how much there is to do.

JI: The book ends with a section about Berlin in the summer of 1945. Why did you want to include that?

CN: I have always wanted to write a piece about the completely chaotic, and as nearly as I can tell, that was Berlin in the summer 1945. And I had read W.G. Sebald’s On the Natural History of Destruction, and this got me thinking about the possibilities.

JI: There is a sort of Iago—someone who is up to some real trouble making—in the book. Where does he come from?

CN: Well, I think everyone is fascinated with the wicked. And I wanted to introduce him into Berlin in 1945 and to do so for a very good reason.

JI: And what is that?

CN: There is something loose in human affairs and we have to be alert to it. While we think we got rid of it in Europe, it is still around. At one time this book was called In the Heart of a Man, which comes from a comment by a 12-year-old boy, Cassius Niyonsaba, who had survived a slaughter outside a church in Rwanda. He said, “I saw how savagery can replace kindness in the heart of a man....”

JI: I’ve noticed that even in this world of the crimes confronting the Berlin police department in 1930 and in 1945, you are still concerned with romance. Can you talk about that?

CN: I’ve noticed that men and women in modern novels are not getting along very well. They sleep with each other, but they are not romantic. They are more hostile to each other than they are considerate. And, as I was writing The Informer, I thought, well, what are you going to do to modulate pages of rock-ribbed suspense and existential danger? So I thought, Hey, how about sex? Now there’s an idea. But then I thought, Well, why not be really daring and try to introduce romance?

JI: Are you tempted to write a different kind of novel—I mean “different" for you? I rarely can write anything that's short; the passage of time seems to almost always be a part of what I want to write. Yet I am always dreaming of writing a short (or at least a shorter) novel. Does anything like this happen to you?

CN: Yes, and on steroids at that. I have a notebook filled with ideas for novels, mostly long ones. For instance, I have an idea for a book that takes place on the Trans-Siberian Express, where a woman tries to come to terms with the most important events in her life. I think I could do it in about 250,000 words. And change.

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John Irving is the author of 12 novels, most recently Last Night in Twisted River. He lives in Vermont.