With Stone Cribs, her fourth Smokey Dalton mystery, Kris Nelscott can lay claim to the strongest series of detective novels now being written by an American author. "Stone Cribs" picks up where the previous book, Thin Walls, left off, in 1969 Chicago. Beginning with her first book, A Dangerous Road, set in Memphis a few months before the assassination of Martin Luther King Jr., Nelscott has been detailing the racial politics of those years.

Here, she ventures into the sexual politics of the years before Roe vs. Wade. Smokey comes home to his Chicago apartment one night to find a woman bleeding to death from a botched abortion in his neighbor Marvella's apartment. He and his girlfriend Laura rush her to the hospital and encounter a doctor who will not intervene to save the woman's life until she names the doctor who operated on her.

That's the kind of detail that makes 35 years ago seem like the Dark Ages. (And with the Bush administration doing what it can to set back abortion rights, with John Ashcroft subpoenaing the names of women who've undergone partial-birth abortions, it's an age we're about to plunge right back into.) As in the previous Smokey Dalton books, Nelscott's method is to make the distance of that past seem immediate.

It was an article of feminist faith, in the era which Nelscott is writing about here, that all women were disadvantaged as a class. Nelscott knows that's a lie. Laura, who's rich and white and therefore able to use her influence to secure treatment for the injured woman, would never, just by virtue of who she is, find herself in the same boat. Yet the fact that this indignity is being done to a woman allows her a kinship that transcends race and class.

The plot has to do with Smokey investigating the underground network of abortion providers, and with the women who try to keep track of those providers, steering pregnant women away from the butchers. It's a measure of Nelscott's control that even when the plot veers into the way the Chicago police used gang violence to their advantage, Stone Cribs never feels as if it's losing focus.

What's strongest in Stone Cribs is how good Nelscott is at calling up the way that blacks, in the law and order of the Nixon years, lived life with the feeling that a gun was pressed to their backs. This is a book about having to toe the line, a state of being reinforced by the fact that Smokey must keep his real identity secret to protect his adopted son Jimmy, a witness to the King assassination, and by the need to keep his love affair with Laura low-key. The conception doesn't allow for much humor, and there's less of Laura in this installment than I'd like.

But Nelscott brings her mysteries both a sense of moral urgency and the instincts of the muckraking social novelist. She's a superb plotter with a steely grasp of how to sustain tension. I have yet to finish one of her Smokey Dalton novels without feeling that she has navigated the divisiveness of a tumultuous time in our collective social history and has not slighted any of the complexities involved. To call her a fine historical novelist is to relegate these books to the past. They read like investigations of unfinished business, a reminder of the wounds those years inflicted that have never healed. Nelscott is fast becoming one of our most invaluable novelists.