In the midst of touring and doing media interviews this month to promote my new psychological suspense trilogy, I find myself explaining, over and over, why I chose the week of September 11, 2001 in New York City as a backdrop for the first book, NIGHTWATCHER (Harper, on sale 8/28/12).

There are many reasons, but the bottom line is this: I’ve always written about ordinary people who are going about their business on an ordinary day and find themselves in extraordinary circumstances; people who cross paths with danger and evil that strikes in a place they would normally consider a safe haven.

On September 11, 2001, that is exactly what happened to thousands of people here in the metropolitan New York area, where I live. By the grace of God, my husband and I weren’t among them. His office was in midtown, and I—having worked in the World Trade Center years earlier—was safely ensconced in the suburbs that morning. I was running late for a commuter train to meet my editor in lower Manhattan when the second plane struck the second tower and made it all too obvious that the city was under attack.

For ten years, I had been writing about the kind of fear that strikes out of nowhere; about waking up in your own bed in your own home in your own town to find that nothing is as it should be and nothing is familiar; about vulnerability in the face of sudden, senseless violence. Now the realization that I was living it, and everyone around me was living it, rocked me to the core. I don’t know anyone who didn’t feel the same way at some point on that terrible day.

With immediate family, close friends and colleagues safely accounted for, I was struck by a couple of things I heard while glued to our local news in the week or so following the attacks.

One: authorities reported that the crime rate dropped drastically in New York following September 11th—the usual crimes, like robberies, rapes, murders—crimes that are serious, to be sure, but paled in the scope of tremendous tragedy. It was a good thing, because the NYPD was distracted and otherwise occupied amid the chaos.

Two: mental health experts discussed the triggering effects a catastrophic event might have on anyone who had already been mentally and emotionally unbalanced.

Three: ...oops, I can’t tell you this one. It would act as a spoiler for the huge twist that unfolds on the very last page of book two, SLEEPWALKER (Harper, on sale 9/25/12), opening the door to the final installment, SHADOWKILLER (Harper, on sale 1/29/13).

Back in mid-September 2001, the “what if” mechanism in my writer’s brain went into overdrive and a premise took shape almost immediately. But it was all too raw to write about at that time. I waited a decade before revisiting the idea.

When I did, details I still clearly remembered worked their way into the book: the jarring drone of fighter planes in the night sky, the unsettling sight of city streets papered with Missing fliers, the stench of burning that hung over the city for months afterward, the way the wind would shift and it would waft in, stopping you in your tracks. I remembered feeling cut off from the rest of the world with cell phones and landline service disrupted that day, relying on email to communicate with my husband, family and friends. I remembered talking to people who lived in lower Manhattan who described feeling as though they were isolated miles from civilization.

That was where I placed my heroine, Allison: in a Hudson Street apartment building beyond the military-manned barricades, in a neighborhood now cut off from the rest of the world to the point where residents who had anyplace else to stay, at least temporarily, gladly did so. Allison did not.

I rounded out my cast of characters with Mack, Allison’s neighbor, whose wife worked at Cantor Fitzgerald and is now missing, and with Rocky Manzillo, a homicide detective who’d seen it all—until that terrible day. Into the mix I brought an enigmatic troubled soul who, in the days leading up to September 11th, was teetering on the brink of violence, fantasizing about it. It wouldn’t take much to push that person over the edge and launch a serial killer’s rampage through a deserted nightscape, preying on women who lived alone in a neighborhood without electricity, without phone service to call 911, without neighbors, even, to hear a scream in the night. And so the stage was set.

NIGHTWATCHER is, like my other thrillers, a suspense novel filled with twists and turns. If you think, halfway through, that you know whodunit—guess again. The sequel, SLEEPWALKER, picks up ten years later, on the anniversary of September 11. Now Allison is married and living in the suburbs, certain the danger is in the past for good when she receives word that the convicted Nightwatcher killer committed suicide in prison. Soon, though, a copycat killer begins working his way through her safe suburban neighborhood, with the same creepy calling card as the Nightwatcher—a calling card only two witnesses outside the police investigation ever knew about. They are Allison, and her husband.

On the last page—the very last line, in fact—of SLEEPWALKER, readers will find one of my trademark “gotcha” twists, and it opens the door to the plot for SHADOWKILLER. It stems from the third interesting detail I gleaned from watching local news coverage after September 11, and if you want to know more about it after you read the book, you can email me or follow me on Facebook and send a message.

I’m on tour this month and next promoting the trilogy. If you live in the New England area, you can find me in Maine this weekend and in Massachusetts Monday night. In upcoming weeks, I’ll be signing in Washington, DC; Ohio; upstate New York; Maryland; Texas; and metropolitan NYC. For a complete tour schedule, check my website at www.wendycorsistaub.com.