A novelist (Rafe Spall) is promised a story that would make him believe in God at the beginning of “Life of Pi.”

The writer was told by a friend to visit a man named Pi whose life story is so unbelievable the writer must hear it from the man himself. Pi, there played as an older man by Irrfan Khan, takes the writer into his home and accepts the challenge. He agrees to tell the tragic but beautiful story of his life.

The film, adapted from the best-selling novel by Yann Martel, begins with the older Pi and the writer sitting together and then flashes back to Pi’s younger days. Growing up, Pi (Suraj Sharma) lived with his family in India, where his parents owned and operated a local zoo. When he was in his teens, Pi’s family decided to move away taking the animals with them.

The boat that is carrying the family and dozens of their animals, however, sinks during a terrible storm and the orphaned Pi is left standing on a small row boat with a few surviving animals. One of the animals—a nasty hyena—soon attacks the injured zebra and the orangutan that have survived the storm. [It should be noted– for parental guidance alone– that these scenes are quite violent and should have earned this movie a PG-13 rating instead of its generous PG label.]

After the hyena has attacked its companions, a tiger jumps onboard killing the hyena and setting up a dynamic where Pi – a young man who was taught to fear tigers as a boy – is left alone on a boat with a ferocious tiger as his only companion.

As he tries to figure out how he can survive a long ordeal with a creature that wants to devour him, Pi seeks guidance from both himself and from religion. His character sees himself as a Hindu, a Christian and a Muslim and understands that his life is part of a larger plan, despite the fact that it’s hard to see how his difficult circumstances are part of that plan.

Ang Lee, the Oscar-winning director of “Brokeback Mountain,” brings this unique story to life despite the fact that much of it takes place with only a tiger and a man onscreen. Through the brilliant use of 3D—which, it turns out, isn’t an oxymoron—Lee creates realistic scenes and animals that seem like they could leap off the screen at any moment.

The story’s major flaw, though, is its narrative structure. The screenplay by David Magee oftentimes seems a bit too contrived. For instance, the way that the film is bookended with the older Pi recounting his tale feels awkward because it disappears for much of the film. Other movies, like “Titanic,” have more seamlessly been able to use that device.

Despite that complaint, and the sense that some scenes with the boy and the tiger drag on too long, “Pi” is a visual achievement that should be celebrated.

Lee deserves credit for bringing this difficult story to life and for capturing it imaginatively in three dimensions.