Lion is halved into two non-equal parts. One is fascinating, the other a grind.

Based on a true story, part one has Saroo at age 5 on the platform of a train station while his brother goes to see about work. While waiting, Saroo explored an abandoned train and fell asleep in one of its cars.

When he woke up, the train was moving and Saroo ended up hundreds of miles from home, alone and in a land where he didn’t understand the language. Unable to communicate or explain where he came from, Saroo becomes a target of criminals of all sorts.

Eventually the boy is caught and put into an orphanage packed with troubled kids. Later, he is adopted by a couple in Tasmania played by Nicole Kidman and David Wenham (300: Rise of an Empire) and becomes Saroo Brierley.

First time major release director Garth Davis and writer Luke Davies (Candy) base the film on Saroo Brierley’s biography. The first half is how Saroo survived his time alone. It is not only fascinating, but it’s dramatic and intense. Sunny Pawar plays the young, vulnerable Saroo and gives an exceptional, often nail-biting performance.

Then the movie flashes forward to the boy’s adult years and the film’s underwhelming second half. Dev Patel (The Best Exotic Marigold Hotel movies) is adult Saroo. He is haunted by images of his real mother and brother, and decides to find them. At that point, he’s in college and in a relationship with Lucy. She’s played by Rooney Mara (Carol), who — along with Kidman and Wenham — is wasted.

For over an hour, you are submitted to Patel’s pathetic whining and moping as he spends countless hours in his room looking at maps and notes pasted all over the walls. Saroo hides from his adoptive parents and his girlfriend until Davis finally drags you to the film’s feel-good payoff.

Many critics are raving about Lion and say it is one of last year’s best movies. Did I see a different movie? Patel — who got a best supporting Golden Globe nomination — is terrible playing a boring character in a boring movie that promises to be a lion but ends up a lamb.