by Dorman T. Shindler is a freelance writer living in Australia.

For the past three installments of the series, Nevada Barr's protagonist Anna Pigeon has called Rocky Mountain National Park her home base. "Hard Truth" (2005) found her battling a human predator in that very same park; and last year's "Winter Study" saw the feisty and fearless park ranger "on loan" to a team studying wolves in Isle Royal National Park on an island in Lake Michigan.

While the latest work, "Borderline," finds Anna still stationed in the Rockies, her Denver-area shrink sends her on a busman's holiday: a "vacation" to Big Bend National Park in Texas. Along with Anna's Denver-area home base, fans of the series may also have noticed successive novels getting more intense. "Borderline" is no exception, with a narrative that plunges readers into mystery, mayhem and a substantial body count by Page 131.

Barr throws readers into the thick of it with a dual narrative following the exploits of Judith Pierson and Darden White, a Texas gubernatorial candidate and her ex-Secret Service agent bodyguard, as well as that of Anna.

Still suffering the trauma of experiencing the death of fellow rangers, being physically attacked (and near death) and — most important — having had to take a life, Anna is in a dark place, psychologically. As Barr writes early on, "She had tried meditating on love and courage, bright satin sashes and whiskers on kittens, but they seemed such tiny points of light in the ink of her internal sky."

Fortunately, Anna has her second husband, Paul, to keep her as upbeat as possible, and a raft full of college students (Cyril, Steve, Chrissie and Lori) to drive her to distraction. Although Barr's skills as a wordsmith are always evident when extolling the often overlooked beauty of nature, her gimlet eye doesn't spare today's youthful generation, either.

Carmen, the river guide/raft pilot/ boat-man, takes Anna and Paul and the four college students down the Rio Grande in Texas' Big Bend country. After a relatively uneventful beginning, Anna persuades Carmen to stop and try to save Easter, a wild (horned) cow that has inadvertently become stranded high upon a ridge in Santa Elena Canyon.

The comical rescue efforts quickly turn serious as the river rises and the rescuers suddenly find themselves in whitewater peril. That breathtaking incident leads to the discovery of a barely alive young Mexican woman who is noticeably pregnant. When the party frees the woman only to watch her life finally slip away, Anna has to perform a C-section. But before anyone in the group can relax, they suddenly find themselves in mortal danger from an unseen attacker.

Deftly folding in the political subplot (the female gubernatorial candidate is in favor of closed borders), Barr manages to weave together musings on life and the afterlife, the hubris of man before nature, current debates on border security in America, and an action-packed plot that all blend quite nicely by novel's end.

If Henry Thoreau, Ian Fleming and Agatha Christie managed to produce a literary child, the result of that weird union would be "Borderline."

While some critics and academics might turn their noses up at genre fiction (deeming it not "serious" enough), they clearly can't see the forest for the trees. Barr's Anna Pigeon series is the best of both literary worlds: careful, craftsmanlike writing and thoughtful prose that meditates on both nature and human nature, backed by a plot that always moves at breakneck speed, leaving readers dizzy, emotionally wrung-out and awestruck.