“Unbroken,” directed by Angelina Jolie, is the story of the courage and endurance of a young American held prisoner, and brutally mistreated, by the Japanese in World War II. With a slow pace and a running time of 2 hours 17 minutes, it is also something of a test of the endurance of the audience. By taking a straightforward biographical approach, broken up only by some flashbacks to fill in the backstory, Jolie achieves accuracy and honesty while giving up narrative intensity and a decisive climax.

The film is based on the nonfiction book by the same title, by Laura Hillenbrand (known previously for “Seabiscuit”). It’s the story of Louis Zamperini, a young athlete who placed eighth in the 5,000 meters in the 1936 Olympics. He is played very effectively by Jack O’Connell, an Anglo-Irish actor in his first big role. After attending USC, Louie enlisted in the Army Air Corps shortly before the U.S. entered the war, was commissioned as a lieutenant, and served as bombardier on a B-24 Liberator in the Pacific Theater.

Zamperini’s plane crashed in the ocean while on a search-and-rescue mission. He, the pilot, and one other crewman survived the crash and climbed into a life raft for what became the ghastly ordeal of floating adrift for six weeks in the hot sun, catching fish and birds to eat and hoping for rain to bring fresh water. A Japanese plane strafed the raft. The third man died after 33 days at sea; Louie and the pilot drifted 2,000 miles before touching land that was, unfortunately, occupied by the Japanese. Thus began Louie’s second hellish ordeal, imprisonment in several camps that ended only when the war did.

Being a prisoner is always awful, but Louie was targeted for special abuse by a sadistic guard named Watanabe, who did everything he could to break the American’s spirit. The guard is played by Takamasa Ishihara, an actor better known in Japan as a somewhat androgynous singer-songwriter and rock band guitarist. He brings a creepily erotic note to his sadistic treatment of the Allied prisoners. Watanabe’s ultimately unsuccessful campaign of cruelty provides the only real rivalry in the film.

And therein lies the problem. We know that Louie will somehow survive and triumph, because otherwise there wouldn’t be a movie made about him. Watching him get beaten time and again is a lot to pay for a brief scene in which Watanabe sinks to his knees, defeated by Louie’s unbeatable spirit.

In other war movies – “Bridge on the River Kwai” comes to mind – at least we have the satisfaction of seeing the bad guys killed (along with some good guys, of course) and the bridge getting blown up. It isn’t widely known, but in the “Kwai” book, the ending is very different. David Lean knew that a successful movie has to have a spectacular ending, so he took the liberty of providing it. Jolie remains faithful to her source and provides a story that is satisfying in its own way, but not one you would gladly see again.