IT'S A CHILLY JULY MORNING on the Wilson River, a deep, narrow stream in northwestern Oregon. The pool below me is clear to the bottom, where I can see a pair of summer steelhead holding. The place just looks cinematic, and that's before you consider the tribe of production assistants and wetsuit-clad effectsmen bustling about onshore. This is day nine of shooting The River Why, the film adaptation of David James Duncan's 1983 novel about fly-fishing, growing up, and Everything Else. I'm eagerly awaiting the next scene, because the crew is about to shoot the most incredible catch in the history of angling literature.

That's saying a lot—fishermen, especially those who write fiction, are liars—but this sequence is pretty unbelievable. Waiting on the bank is 27-year-old actor Zach Gilford—best known as introverted high-school quarterback Matt Saracen on NBC's Friday Night Lights—who plays the novel's hero, a troubled fly-fishing prodigy named Gus Orviston. Gus stumbles upon The River Why's heroine, a blond fishing goddess named Eddy, as she hooks a huge steelhead with a homemade hazel pole, tosses the rod into the river to slow the fish, sheds her clothes, and subdues the leviathan by swimming after it and grabbing it underwater. Only the most imaginative of anglers could have dreamed up such a catch, which has achieved mythic status among fishermen in the 26 years since The River Why was published.

Alas, there's a holdup. While a producer readies a dead hatchery-raised steelhead for the scene, word comes down that an overzealous makeup artist has delayed the actress playing Eddy, 22-year-old Amber Heard. Director Matt Leutwyler greets this news with incredulity, raising his megaphone. "You don't need to do her makeup!" he yells. "She's going swimming!" Nearby, executive producer and screenwriter Thomas Cohen looks at his watch, shaking his head. There are only 14 days left to wrap filming, and the last thing anybody wants is further delays.

Cohen and Leutwyler hope to premiere the movie at Austin's South by Southwest festival, in March, and find a distributor soon thereafter. But no matter when The River Why hits the big screen, it will face the kind of scrutiny that's rare for an independent film. Since it involves both salmonids and flies, The River Why will invite comparisons with A River Runs Through It, Robert Redford's bigger-budgeted 1992 hit. But Leutwyler, Cohen, and Cohen's wife, producer Kristi Denton Cohen, face other challenges, too. With a lean budget and a guerrilla shooting style, the film's brain trust is trying to bring to life a deeply complex, revered story of self-discovery in the American West. And they're trying to accomplish this without the cooperation of the book's author, who has done everything short of sabotage to stop filming.