Gorky Park (1981) - I already reviewed this once before on this blog, but I have recently read some of Smith's other works featuring lead character Arkady Renko (I also tried to read Stallion Gate but didn't get into it; will try again at a later date). Anyway, Gorky Park is about a Russian investigator with the Moscow police who uncovers three corpses missing their faces. Smith paints a portrait of Soviet society that is neither scathing nor apologetic, with an intriguing plot and many quality characters. Some books seem to get better with each read, and this is one of them.
Polar Star (1989) - I thought an entire book set on a ship was going to be a very odd sequel, but it turned out to work incredibly well. The story revolves around Renko hiding from the KGB by working on a fishing vessel in the arctic sea, until a corpse is found in the fishing nets and Renko is asked by the captain to find out what happened to her. Ships are not terribly interesting to me, and the world on a ship can only be fleshed out so far, but Arkady Renko is just top notch in this book. His character is strong with appeal, charisma, and a dry sarcasm that makes him endearing but not obnoxious. The mystery itself is serviceable, clever at intervals, but it's the characterization that carries the novel. Even the supporting cast is full of interesting men and women. Some aren't all that fleshed out, but the major ones are, and provide good support for the lead character.
Red Square (1992) - At least half about Russia more than the crime, Red Square's biggest stength is the backgrounds of the story itself. Renko returns to Moscow to find the city vastly different than when he left it, looking more like Beirut in the late 70s than the cultural capital of the USSR. The book takes about 100, 120 pages before the mystery begins to become enticing. Normally you would lose me before then, but the descriptions of Soviet life in the end days are quite compelling. Although not part of a trilogy, Red Square is the third novel in the "Arkady Renko series," and so it suffers from some of the flaws of the last film of a trilogy; for example, it far more uplifting than either of the previous novels. In fact, Polar Star may be the darkest of the three books, so that also kind of fills in with the trilogy theme. There is a bit of deus ex machina here and there, but it's not offensive. There are times when the mystery gets very interesting, and others when the book is only carried by the strength of its world.
My only other comment would be the series suffers from Terminator Chronology Syndrome. Just like the Terminator films, the chronology really doesn't add up. Gorky Park in my mind is set in the late 70s, and the book was published in 1981. Polar Star is more nebulous; it seems like it's set around 1987, but I could see it work around 1984 or 1985. Red Square is quite specifically set in August of 1991, which would mean going backwards would set Gorky Park circa 1986, or if generous, 1985. While possible (the film was released in 1983), the feel and context of the book just don't work that late in the 80s. It's not a major issue, mind you, but if you enjoy context, it could be a small irritant.