When the series opens, Gregor has retired from twenty years with the FBI. His last ten years were spent setting up the unit that pursued serial killers, and when his wife's final illness with cancer is consuming both of them he cannot be there for her and keep up that intense work. Once she dies, he has no ambition to return. He moves back to his old Armenian neighborhood in Philadelphia. When he grew up there, it was a typically poor immigrant neighborhood. Now it is still ethnically Armenian, and most people living there are ones he grew up with, but it is no longer poor. He befriends Tibor Kasparian, a priest of the Armenian Orthodox church, who grew up in an Armenia under the thumb of the Soviets, and who spent much of his adult life in prison either in Armenia or the Soviet Union. Now he lives in a church apartment that is wall-to-wall books.
Gregor gets involved in a murder of a wealthy man living in Philadelphia's Main Line incidentally. The man, Robert Hannaford, asked Demarkian to dinner to consult with him, but when Gregor arrives Hannaford is dead by murder. He has seven children and a wife, and it seems that one of the family must be guilty. One of the children is Bennis Hannaford, a beauty who writes best-selling fantasy novels. Once the murder is solved, Bennis moves into Gregor's building and becomes a part of the community in the Armenian neighborhood.
Haddam begins each book by getting into the heads of the main characters. It isn't until a good way in that the murder happens and Gregor becomes a part of the story. Haddam's characters run the gamut of humanity: rich, poor, smart, stupid, Christian, Wiccan, atheist, men, women, liberal, conservative... and so on. Since she shows us what they are thinking, they become spookily real and through them the complexities of the community, and indeed, the human condition, are revealed.
Since Gregor was a law enforcement professional, she avoids the nonsense of an amateur who just happens on all these murders, though Gregor runs into them by happenstancee too often. It does get a little frustrating how often Gregor knows who did the murder, but won't tell anyone until he has proof that will stand up in a court of law. One thing I really do like about the series is that most of the professional law enforcement people depicted in the books are eager to have Gregor's help and are good at police work. I get really tired of the amateur sleuth whose run ins with the police are always unpleasant because the police are short-sighted and obnoxious.
It is a great series that never grew stale for me, and i hope will keep going. Haddam's website is worth a visit, too. It doesn't seem to have been updated since 2004 or so, but has some great essays on it.
There were times I got a little tired of the series, but every time I got hold of a new volume I devoured it and wanted more. There are a lot of recurring characters that were wonderful to visit with again and again, and always new characters in new situations. Besides, you have to love an author who in chapter headings quotes St. Theresa of Avila alongside Terry Pratchett.