The City That God Forgot : THE FOURTH DURANGO <i> by Ross Thomas (Mysterious Press: $18.95; 312 pp.; 0-89296-213-5) </i>

“The Fourth Durango” opens with the mayor and the chief of police waking up in the same bed. And that’s pretty much the way the rest of the story goes: from one unexpected--sometimes inexplicable--turn to the next.

Durango, Calif. (non-existent to my best geographical efforts), must line up well behind the Durangos of Spain, Mexico and Colorado. Thus making it the fourth Durango. So far removed is it from the mainstream that its motto is “The City That God Forgot.”

Mayor Barbara Diane (B.D.) Huckins long ago decided that if the mission-less city could not hack it as a tourist attraction, despite “the most salubrious climate on God’s green earth,” it would provide privacy, a sanctuary, a hide-out--when the price was right.

Jack Adair, formerly a state supreme court chief justice and fresh from a penitentiary where he was sentenced for income tax evasion, needs a hide-out. There is a $20,000 price on his life. Or is there?

The beginning of a proliferation of coincidences occurs as Kelly Vines finds Durango for Adair. Vines seemingly is Adair’s one and only remaining friend.

Vines is also: (a) a lawyer disbarred for his part in saving Adair from a trumped-up bribery charge (b) Adair’s son-in-law and (c) former roommate of Adair’s dead son, allegedly a suicide.

Vine passes the screening test administered by the regularly horizontal Dixie, half-sister of Mayor Huckins. So, having sufficient funds, Vines and Adair qualify for admittance to Durango.

Then things begin to happen.

A total of nine murders moves the plot along. All committed by a man described as, “five-foot-two, and chunky and fat. Mud ugly and had this funny nose with one hole twice as big as the other. Couldn’t help notice, it sort of turned up and took aim at you.”

Now there’s an easily identifiable villain. Each time a short, fat, decidedly porcine man--or his pink van for that matter--shows up it’s like the shark theme in “Jaws”; you know somebody’s in a lot of trouble.

This is not, strictly speaking, a whodunit. The author Ross Thomas tells us clearly who this homicidal maniac is.

But there is a puzzle, a mystery. It’s couched in a deliciously clever clue. The sort of clue that puts a satisfied smirk on the face of mystery buffs. I wouldn’t for the world tell you what this clue is. Only that it’s there.

Thomas, author of more than 20 novels, gives us distinctly three-dimensional characters, people we come to know and are interested in.

For instance, there’s B.D. Huckins, 36, who renamed the city park after the former mayor, the man she had defeated. Was it a gesture of civility? A mark of respect for a vanquished foe?

Or is it, as someone suggests, a reminder that if you challenge her you could become a monument?

At another juncture, Merriman Dorr, owner of a restaurant and poker den, offers to transport Kelly Vines anywhere any time only because Vines and Adair are important to Huckins. “I’ll do it for free gratis,” Dorr says.

“Why’s everyone so willing to jump off tall buildings for her?” Vines asks.

Dorr replies, “Because if you offer to jump today, you might not get pushed tomorrow.”

Or Jack Adair: On his final day in prison he is about to be assaulted (that $20,000 price tag on his head), when he is saved by Blessing Nelson, a gigantic man Adair has paid $500 a month to protect him. Adair thanks Nelson profusely. Nelsom comments: “Never shuts down for rest or repair, does it--that mouth of yours? Just goes on and on, night and day.”

And so it goes for all the characters populating “The Fourth Durango.” Through marvelous passages of description and anecdotes they come alive for us and remain true to their varying and differing personalities.

If there is a caveat to this book, it would have to do with the plot: its coincidences, complexities and layers.

Consider the poverty-level family that discovers an abundance of natural gas under its land. Instant nouveau riche. The night they learn they’ve got a “barn-burner,” the father, Obie Jimson, becomes a not-very-convincing suicide. His son is convicted of the murder. The conviction is overturned on appeal by the Supreme Court led by Jack Adair. Someone tries to frame Adair and Associate Judge Fallon for bribery. The same someone, as part of the frame, murders Fallon and his wife. The same perpetrator turns out to be a one-time associate of two of the characters we’ve already met in Durango. He also happens to be the long-lost brother of one of the members of the Jimson Family, whom he kills. Kelly Vines represented clients interested in the Jimson land.

That’s lots of layers of coincidences and complexities.

I would have preferred one more chapter that tied up all those loose ends and saved my having to go back in the book to find them.

Nevertheless, this is an entertaining book that can be pleasantly devoured in a sitting or returned to in satisfied anticipation.