My father-in-law, who lived to be 96, came to this country from Warsaw in early 1939, six months before Europe was plunged into war.

He never had any idea what fate befell his parents or any of his extended family; he was the only one to survive. His entire life, it was like he carried a weight around with him, a mantle of guilt and loss; peace seemed to elude him, despite his successes here. Like a lot of survivors, he never spoke a word to my wife or her brother about his family life back in Poland; the yoke of memory was just too hard to bear. He came here as a student, but in 1941, when the U.S. entered the war, he enlisted, and because of his facility with languages, he was placed in the Army Intelligence Corps. Similarly, he never divulged a word of what his duties were there.

As for me, I write suburban thrillers. Over the past decade, I’ve published nine of them, all about recognizable, everyday moms and dads in an upscale setting who, through either a momentary weakness or misstep, end up over their heads in something sinister. I’ve had success with them—five have made the New York Times bestseller list, and all but one have been Top 10 in the U.K.; I’ve been published in more than 20 countries.

But for several books now, I’ve felt pigeonholed by the narrow niche of what my publisher, and perhaps even my readers, expect from me: the familiar suburban setting, the root for–able yoga moms and hedge fund dads, the crisply paced plot-driven story lines with a coda of some emotional resonance at the end (a carryover, perhaps, from my days cowriting with James Patterson). It was how my publisher positioned me. There was a strategy and a goal. I went along willingly. I was writing good books—exciting, suspenseful. They were just not the books I had always intended to write.

My favorite stories growing up were the sweeping tales of the Persian-Greek and Trojan wars, the First Crusade, escapes from Devil’s Island, the clash of Napoleon and the tattered Russian army, Nazi conspiracies that lay buried in test tubes in Brazil or the search for ODESSA long after WWII—stories that transported you, not just grabbed you. Probably the book of mine that I recall with the most satisfaction, cowritten with James Patterson, was of a 12th-century peasant who comes back from the First Crusade to find his wife abducted and daughter slaughtered, and who dons the tattered tunic of a jester to avenge them.

The truth was I felt like I was perpetually pushing a boulder uphill, continually having to come up with fresh and gripping traps for my characters to fall into, in similar settings, with similar things at stake. I wanted to write books with bigger bones, broader themes, and richer, more atmospheric settings. I had come to a corner in my career, and my father-in-law’s story was staring me in the face. I decided to let the boulder fall.

The One Man is the story of an escaped Pole who is determined to return to Poland, where his parents were murdered by the Nazis, to rescue the one man the Allies believe can ensure their victory in the war. That man is an atomic physicist whose expertise is urgently needed on the Manhattan Project, but he’s imprisoned at Auschwitz. It’s a thriller in the sense that it’s about a near-impossible mission with a ticking clock, but it’s much richer in theme, more deliberate in characterization, and with a far more detailed setting than anything I have ever done.

Writing this kind of book was not without its risks. Would fewer publishers bid for it? Would some of my readers not follow me? As a Jew, taking on the Holocaust is an imposing responsibility, and it was an artistic risk. But I reminded myself that it was far less of a risk than getting into this business in the first place.

I have no idea if The One Man will deliver the crossover audience I am hoping for, or how it will stand up against the body of work already written on the Holocaust. I only know it came out richer and better than my most ardent hopes for it, and that my next books will continue in the same vein. And that my father-in-law, after reading a few chapters before he died last February, put it down with tear in his eyes, turned to my wife, and said, “Lynn, there are some things I’d like to talk to you about.”

Andrew Gross’s novel The One Man will be published on August 23 by Minotaur Books, a division of St. Martin’s Press.