The true story of a young boy separated from his family and his 25-year journey to find them in Garth Davis’ first film “Lion” roared at the Toronto film festival Sunday.

Adapted from Saroo Brierley’s autobiography “A Long Way Home,” the film stars Dev Patel, Nicole Kidman and Rooney Mara, who is also appearing at the festival in “Una” and “The Secret Scripture.”

It sees Saroo, a precocious 5-year-old who follows his older brother around everywhere, become separated from him one night on a train platform in their native Madhya Pradesh.

Soon, Saroo finds himself nearly a thousand miles away in Kolkata, where he does not speak the language.

There, he is picked up off the streets and placed in a government orphanage before being sent to Australia for adoption.

In his twenties, living in Tasmania, Saroo starts to wonder what happened to his brother and birth mother, and so begins an obsessive search.

He scours satellite imagery and online maps to try to locate his hometown, matching landmarks to childhood memories.

But delving into the past threatens the present, and he becomes adrift.

“He had his past family and his present family and when Saroo starts to search and becomes obsessed, you start to see a tug-o-war between his choices: choosing the past you sacrifice the present,” Davis said.

The film marks Patel’s return to the Canadian city that launched his film career.

Director Danny Boyle’s “Slumdog Millionaire,” which starred Patel as a teenager from the slums of Mumbai accused of cheating on a television game show, won the Toronto film festival audience prize for best picture in 2008 before going on to win an Oscar.

“I rocked up here with ‘Slumdog’ in my school shoes and a borrowed suit and it’s good to be back here with a bit of facial hair with this (film),” Patel told a press conference.

The Briton said in the years since “Slumdog,” he has made four more movies in “beautifully chaotic” India that gave him an appreciation of his ethnic roots.

“It’s weird, because I spent most of my existence in school (in Britain) trying to shun my heritage to avoid getting beaten up or bullied and just to fit in,” he said.

“And then I discovered India with Danny Boyle and I was completely struck by lightning. It's just so enthralling to me,” Patel added.

“It sounds so cliche but I understand myself and where I come from more and more, and that’s something I could feel in Saroo‘s character too: We’re products of two different worlds.”

In “Lion,” Patel plays an adult Saroo who is more Australian than Indian.

For Kidman, who is herself an adoptive mother, the story evoked a “visceral reaction,” she said. “It was very, very emotional for me.”

“For me, this is a film about the power of mothers, whether they're biological or adoptive,” she explained. “I said to the real Saroo (when they met): ‘You have two mothers, lucky boy.’

“For a child to be loved and to grow up in a family with love is the most important thing, however that family comes together,” she said.

Patel agreed: “I think adoption is a beautiful thing, to be able to give someone a second chance at life.”

The film takes audiences through gritty Indian neighborhoods, showing the difficult living conditions in the poorest parts of India, but also finds beauty in the landscape and the relationships Saroo develops.

Davis said aerial shots in particular were inspired by Saroo’s “psychic connection to his mother” and Google Earth, which Saroo used to track down his hometown.

“Saroo told me that every night he imagined himself going to India, walking those streets, going into that little house and whispering into his mother's ear ‘I’m here.’ For me, it was like an astral projection, or out of body experience,” Davis said.

The making of the film, he said, also opened his eyes to the plight of millions of lost children around the globe and his producers are now in talks with a childrens’ charity to try to help.

“I became much more aware of the plight of these children. Right now, there are so many children in need,” Davis said.

“I hope this (film) is one step toward some sort of dialogue.” (AFP)