When author Erik Larson started research for his latest book, Dead Wake: The Last Crossing of the Lusitania, about the 1915 sinking of the luxury ocean liner, he wasn't expecting many surprises. As with the Titanic, everyone knows the ending: Almost 1,200 passengers died when a German submarine torpedoed the ship off the coast of Ireland.

The attack has widely been seen as a catalyst for the United States' entry into World War I, as Pearl Harbor was in World War II. Except it wasn't. Two years passed before America got involved, and President Woodrow Wilson never mentioned the attack. That was just the first of the surprises Larson found.

Known for narrative nonfiction books such as The Devil in the White City and In the Garden of Beasts, Larson started his writing career as a reporter for the Bucks County Courier Times and then went to the Wall Street Journal.

Larson will appear Wednesday at the University of Delaware Library Associates dinner in Wilmington, and on Thursday, he will speak and sign copies of his book at Stetson Middle School in West Chester, sponsored by the Chester County Book Co.

You've mentioned the phrase "the dark country of no ideas" to describe that gray area when you're searching for your next book idea.

It was coined by my publicist. We've worked together on five books. I'm not like other writers whom I envy who have a whole list of ideas ahead of me. For some reason, when I finish a book, any other ideas I might have had that were contenders, they just die. I'm always a blank slate. Because this kind of history, this narrative nonfiction, it's history told in a compelling way, and it's hard to find ideas that lend themselves to that kind of telling. So to find a story that has all the components - it's not easy.

I'm very grumpy during that period. I'm in that phase right now, so don't mess with me [said jokingly].

When you hit on something, like the Lusitania, is it an instant yes, or do you poke around at three or four things before deciding?

It's almost never an instant yes. Between books, I keep an idea journal, and I have a running list of potential contenders. Some of them are things that could be books but aren't subjects I want to spend the next four years on. Through a process of percolation, if one comes to the surface, I'll do some advance reading, I'll go to the library and get a bunch of books.

I knew a lot had been done about the Lusitania. We learned about it in high school. But I decided, "OK, I'll read about it" and took out a bunch of books and was instantly intrigued. I did not know much about the sinking itself - that's the stuff they leave out of the history books.

As part of your research, you went and looked at photos from the site.

Seeing the pictures was an important element, not so much to confirm that it happened, but to see that it happened to real people, ordinary real, live people, including kids. It was really valuable, because when I looked at them, I wasn't just seeing someone who died, but as a trove of details about the time and that person in their last moments. It was very powerful.

You also took some trips on the Queen Mary to get the feel of being on a ship.

I took two voyages - and the captain of the Queen Mary is very adamant on the subject, that it's a voyage and not a cruise. I had no interest in the engine room or a tour, but I felt it was very important to do a transatlantic voyage to get a sense of what it was like. It takes seven days, and what I gained from that really informed the entire book, and that's the sense of tedium. Once the first day is over with, you've got six days in the middle of the ocean, and the only thing that breaks it up is food and booze. And the passengers on the Lusitania had that same experience with food and booze and socializing - but with the added layer of an underlying sense of dread, because what if a submarine comes and tries to sink them?

What surprised you when writing this book?

When I'm surprised, I figure readers will be surprised, too. I'd hoped, setting out, that it would turn out that the submarine commander would be a classically brutal character with a scar down his face. But it turned out that he was a handsome, kind, moral, well-loved guy. I love that nuance, that no one is ever a complete hero or villain except Adolf Hitler.

It seems as if the public is endlessly fascinated with nonfiction narratives. What's the pull?

I don't know, but it's so distressing to me that it's harder and harder to find ideas that no one else is doing. I can't claim to have gotten there first.


Erik Larson: "Dead Wake"

7 p.m. Thursday at Stetson Middle School, 1060 Wilmington Pike, West Chester.

Tickets: $17, includes softcover copy of book and admission for two.

Information: 610-696-1661 or www.chestercountybooks.com

(Also 6 p.m. Wednesday at the University of Delaware Library Associates' annual dinner in Wilmington. Tickets: $175. Information: 302-831-2231 or UDLA@udel.edu.)