When Linda Fairstein was writing her third novel, she already had the setting in mind for her fourth.  It was Gothic ruins she passed every day on her drive to and from work in the Manhattan District Attorney's office, where she has been chief of the Sex Crimes Bureau for more than 25 years.

The ruin that Fairstein had been gazing at over the years from FDR drive, especially when it's "lighted dramatically at night, with its pointed, arched windows and crenellated roofline," was the Smallpox Hospital on the southern tip of Roosevelt Island.

Fairstein talked about the hospital, her new book, The Deadhouse, and the history of the Island during a Meet the Author hour at the Barnes & Noble bookstore on 66th Street last week.

Until she began research for her book, the fourth mystery in the Alexandra Cooper series, Fairstein didn't know what the building on the Island had been, just that it was a beautiful and haunting sight.  She found out what it was at the New-York Historical Society Museum library, but she learned much more, she said, when she contacted the Roosevelt Island Historical Society and met with Judith Berdy, who, Fairstein told her audience, is the Historical Society.

Berdy provided her with background on the building and the Island, showed her old photos of the hospital inside and out after it was abandoned by the City, and even arranged for Fairstein to travel beyond the locked gate to view the ruins close up.  Fairstein had her photo taken there as well as other shots of the ruins, two of which appear on the book jacket.

She gives Berdy special credit in her book for helping with the research, saying Berdy shared her "passion for Renwick's stunning skeleton."  James Renwick, architect of St. Patrick's Cathedral, designed the hospital in the mid-1800s.  Fairstein described her research to her audience at Barnes & Noble as so satisfying that she had to be reminded to end it and actually start writing the book.

Besides the protagonist Alex Cooper, a Manhattan sex crimes district attorney like Fairstein, and homicide detective Mike Chapman, who helps her solve cases, Roosevelt Island, both past and present, stars in the mystery.  Indeed, the climactic scene takes place on its rocky shoreline.

The setting of the Smallpox Hospital gives readers a chilling reminder of recent headlines.  Fairstein's writing seems prophetic in a conversation between her protagonist Cooper and a college professor about who would profit from a study of the hospital's history.  The professor says:

"There's enormous debate in the field of medical ethics about whether or not the smallpox virus should be completely eradicated when the disease is conquered worldwide.  Since you need the actual virus to make the vaccine, does one save a small amount of it against the day that some form of the pox reappears in the world? And who is the keeper of the deadly virus?  Who do we trust not to engage in germ warfare?"

Fairstein put her research to good use as she packs a lot of detail in the book about the Smallpox Hospital, the nearby Strecker Memorial Laboratory, the famed Octagon lunatic asylum near the northern end of the Island, and the history of the penitentiary, now just rubble near the lab and hospital.  And the "deadhouse" itself?  Its location is a matter of speculation until the final chapters.

Sharp-eyed Islanders will find a few errors.  The Meditation Steps and Blackwell House are reversed in the map key in the front of the book and Fairstein takes poetic license in her description of the arrival and departure of the Tram cars.  But for many residents, the historical information in The Deadhouse, including the story of a prison scandal, should be a revelation.

The case that Cooper and Chapman must solve is the murder of King's College professor Lola Dakota, who is found at the bottom of the elevator shaft in her apartment building.  The cast of suspects includes her abusive ex-husband and other professors who, with Dakota, are studying and excavating sites on Roosevelt Island.

Fairstein said she was interested in the competition between college professors and used that in this mystery, along with the Roosevelt Island research.  She also satisfied a request from some of her readers who wanted to know more about Chapman's personal life.  Fairstein obliged in this book, giving him a new romantic relationship with an architect.  She also cleverly lets Chapman, described as a history buff in her earlier mysteries, present some of the history of Roosevelt Island in an early chapter.

Island residents may be particularly interested in one of the ideas in the book – the question of restoring the ruins.

Residents will have a chance to meet Linda Fairstein and hear her talk about the book and the research for it when she appears at 7:00 p.m. Tuesday, Nov. 13, at the Island branch of the New York Public Library on Main Street next to the Thrift Shop.

The book is available at most commercial book stores.