By Jordan Riefe

LOS ANGELES (Reuters) - On its surface, new movie "Salmon Fishing in the Yemen," tells of a fishery expert tasked with creating a salmon-filled stream in the Middle East country's waterless desert, but underneath that description is a tale of making dreams come true.

The movie, which is based on Paul Torday's 2006 debut novel of the same name, opens in major U.S. cities on Friday with plans to expand around the United States in weeks to come.

Its star Ewan McGregor and director Lasse Hallstrom said they were drawn to the project, in part, by its tale of faith, hope and love, and after problems in production, it seems all three were necessary in bringing the tale to theaters.

"One of the observations of the script is that it is important to try to have faith and hope in making your most impossible ideas becoming possible," Hallstrom told reporters recently.

McGregor portrays Fred Jones, a Londoner who is awakened from his gray, dismal life to help an Arab sheik pursue his dream of fly-fishing for salmon near his home in the desert.

Jones initially considers the idea an act of sheer folly, but as his adventure leads to love, he comes to understand that a task which at first seems wildly out of place can sometimes lead to a profound understanding of one's own life.

Swedish director Hallstrom said he knows how powerful faith can be. "Moving to America, that was quite a leap," recalled the director who gambled with his comfortable career back home when he moved to Hollywood on the heels of his 1985 breakout, "My Life as a Dog," to pursue a career making U.S. films.

Hallstrom went on to direct movies such as "What's Eating Gilbert Grape" and "Chocolat," and he earned an Oscar nomination for his "The Cider House Rules."

"You take leaps daily when you make a film," he said. "You have to let the camera roll and just keep your belief that the magic moment might happen when you've almost given up on it."

KEEPING THE FAITH

To hear Hallstrom and other members of the production tell it, they could have easily given up on trying to build their own stream in the desert for the movie.

he production encountered problems when unprecedented rains in Morocco's Atlas Mountains near where a set was built unleashed a flash flood that swept away the film's fishery.

Production raced to rebuild, but that construction also was hit by a midnight flood. After rebuilding a third time, seven days before the cast was due to arrive, a 12-foot wall of water swept the set away again.

But they were undeterred and rebuilt a fourth time. The entire experience left McGregor wondering about the "impossible is possible" theme of the movie.

"I do believe that things are achievable," said McGregor, the son of a school teacher and a physical education instructor who always assumed their son would settle down one day and pursue a real job outside of acting.

"I've never really listened to those voices," said McGregor who is a bit of a dreamer himself.

In Spring 2004, he and friend Charley Boorman left London on motorcycles and traveled through Europe,Russia, Siberia and Canada, eventually winding up in New York City. McGregor said some people saw the journey as foolish, but it spawned a TV series, "Long Way Around," and a book  by the same name. book

Along the way, the two travelers chose to highlight UNICEF outposts such as one in Chernobyl that works with childhood leukemia and cancer sufferers who were victims of the nuclear disaster suffered by their parents.

Through that effort and other charitable work, McGregor said he has seen people achieve what others thought was impossible.

"We all choose work that we can put our heart and soul into that stands for something," offered McGregor. "Even if it's just entertainment, maybe that's a worthwhile thing to do."

Hallstrom added that "if you have a passion for doing something, you have to go with your passion and fulfill it.

"You have to keep those impossible dreams alive and make them come true," he declared. "I think that's a wonderful message."

(Reporting By Bob Tourtellotte)