When Lou Ureneck was a young man, the future he envisioned centered on one certainty: He would never get divorced. He would always be there, a father to his children.

He knew well the pain of divorce. When Ureneck was 7, his father abandoned the family. He never saw or heard from him again.

His mother remarried a charismatic charmer. Johnny Kababick took Ureneck fishing in central Jersey and returned from his voyages with the merchant marine brimming with enchanting stories. He was "the kind of father every boy wants to have," Ureneck recalls.

But one Saturday afternoon, after escalating marital clashes, Johnny walked out, without packing clothes or saying a word, and never came back.

And so when Ureneck married a pretty girl from Portsmouth, N.H., and fathered two children of his own, Elizabeth and Adam, he vowed that he would give them a "normal life," a life that was rooted and secure, with both parents living happily under the same roof.

"Divorce - I couldn't even conceive of it," Ureneck says. "I'd never let it happen to me. It would not be part of my life. . . . But guess what? Life has a way of surprising us."

Ureneck tells of the terrible toll of his divorce - on himself, his son and their relationship - in a beautiful book, Backcast: Fatherhood, Fly-fishing and a River Journey Through the Heart of Alaska (St. Martin's Press, $24.95). Ureneck will read from the book at 2 p.m. Sunday at Barnes & Noble in Exton.

An adventure story wrapped around a memoir, it chronicles a fishing trip Ureneck took with his son in the summer of 2000. Adam, a newly minted graduate of Germantown Friends School, was smarting from his father's devastating decision to part from his mother. Ureneck, a former Inquirer editor, was struggling with guilt and the conviction he had failed as a husband and father.

"My life was in a ditch: I was broke from lawyers, therapists and alimony payments and fearful that my son's anger was hardening into lifelong permanence," he writes.

"In the last few years, I had met many men who no longer had any contact with their children because of a divorce. These men didn't see their children at holidays and missed their graduations. . . . I couldn't bear the thought of losing my son. I wouldn't let it happen, even if it meant taking the risk of a self-guided and underfinanced trip to Alaska."

The trip begins inauspiciously. The weather is foul; the mosquitoes, relentless. Ureneck's homemade map of the wild Kanektok River is inadequate. Adam is surly and sullen, rejects his father's diffident attempts to exert paternal authority, and misses no chance to express contempt and criticism. The exchanges between them are strained and awkward.

"Meeting angry bears and getting lost in the woods was scary," Ureneck says, "but not half as scary as the prospect of losing my son."

Backcast is bejeweled with reflections about fatherhood and philosophical musings about the soul-soothing pleasures of fishing in general and fly-fishing in particular.

"Religion and fly-fishing offer certitudes in a disorderly life," Ureneck writes at one point. At another, he describes the essence of the sport: "Playing a fish is a form of jujitsu. It is a contest that rests on a single cruel irony. One of the combatants has knowledge that the other lacks: the futility of the struggle. An old, smart fish understands the game. It will not fight back. It holds in the current, confounds the fisherman, and stalemates the battle. For the skilled fly fisherman, the art of fighting fish is this: to balance the loss of the fish from a broken line against the death of the fish from exhaustion."

It's because of such writing that Backcast won the National Outdoor Book Award and that reviewers lavished it with praise when it was published last fall (Bill McKibben: "One of the finest meditations on fathers and sons that I've ever read").

Ureneck, 57, who is chairman of the journalism department in the College of Communication at Boston University, began the book in the spring of 2003. He was eager to undertake a long writing project and to understand "this painful experience I had just been through."

"Initially, I thought it would be a book almost entirely about the trip down the river. Then, as I got into the telling of the story, I found myself looking back further into my own childhood, as if pulled by an undertow."

Ureneck's childhood was, to say the least, remarkable. His strong-willed Greek mother supported her two boys by running a succession of beauty salons. The family kept its belongings to a minimum; it made moving at the spur of the moment, often a step ahead of enraged landlords, easier. Ureneck and his brother became skillful at dodging bill collectors. By the time he left for college, he had lived in 17 houses or apartments.

He coped with the turmoil and instability in part by growing thick emotional cartilage - "a world-class ability to suck it up." For comfort, he turned to the woods, "that old and inexplicable companionship of trees, grass and river," and his beloved fishing.

"At some level, the book really is about mastery," Ureneck says. "How do you make a life? One of the ways I learned to be capable at a very early age was to go fishing, to be outdoors and self-reliant. So while the fishing was fun, it was also giving me something valuable - a way to cope and learn and move forward in my life. As it turned out, ironically, when I had big trouble with my son, we had the fishing."

In tracing the arc of his own life as fatherless son and nearly son-less father, Ureneck illuminates abiding truths. To wit: Men, emotionally clumsy creatures that they are, happily communicate through silence. They express their affection by doing, not talking.

"What happens in the story?" Adam asks while he and his dad are discussing Hemingway's classic fish tale "Big Two-Hearted River."

"Not much," Ureneck replies. "At least not much that you can see. Mostly you feel it. It's a story where all of the meaning is unspoken."

During their river sojourn, Ureneck and Adam share few, if any, profound and cathartic words, judging by the book. Yet their merely being together, their sharing the same reckless adventure, draws them closer. Doggedly, Ureneck shows his love for his son by giving him the most precious gifts a father can bestow: time and attention.

"One of the reasons Adam and I came through this OK is that we had formed such a close relationship when he was little," Ureneck says. "I spent a lot of time with him and enjoyed every minute of it. . . .

"Families hit rough water, and I guess the lesson of the book is to trust in love, to hang in there. Divorce doesn't have to be the end of the world, and there are times when divorce is the right thing."

Since the book's publication, Ureneck has received letters and e-mail from grateful readers. But the best response came from Ureneck's son. Now 26, Adam is serving the poor in Peru and preparing to become a Roman Catholic brother.

"He sent me an absolutely beautiful letter," Ureneck says. "He wrote, 'I understand things a lot differently now. I understand you and myself better. You never have to worry about losing me. I'm hooked.' "