Dev Patel film Lion roars into Toronto

Dev Patel plays the adult Saroo in Lion

Eight years after making his debut in Slumdog Millionaire, Dev Patel is back with another film that features an impoverished Indian boy on a life-changing journey.

And like Slumdog, which won eight Oscars, Patel's new film Lion is now being talked up as a major awards contender.

But that's about where the comparisons end.

"Thematically and tonally the films are completely different," said the 26-year-old British actor after the film's world premiere at the Toronto International Film Festival.

"Slumdog has a frenetic energy and this film is a sweeping story... it's a mothers and son story,"

Lion tells the true story of Saroo, a five-year-old boy who becomes tragically separated from his family after he boards a train and is transported hundreds of miles from his rural village.

He ends up in a Calcutta orphanage from where he is adopted by a couple in Australia, played by Nicole Kidman and David Wenham.

Twenty-five years later Saroo attempts to use Google Earth to find his way home.

The film has an emotional punch that saw many in the audience wiping away tears at a press screening in Toronto on Sunday.

Patel plays the adult Saroo, while newcomer Sunny Pawar puts in an unforgettable performance as the young boy.

It's Patel's fifth film shot in India.

"I spent most of my existence in school trying to shun my heritage to avoid getting beaten up or bullied or just to fit in," he recalled.

"And then I discovered Bombay with [director] Danny Boyle for Slumdog. It struck like lightning. It's so enthralling for me to go back.

"Working in India is beautifully chaotic."

'The power of mothers'

Nicole Kidman said that as a mother with adopted children she had found Saroo's story "very, very emotional".

"For me this is a film about the power of mothers whatever form they come in - whether they are biological or adoptive.

"I said to the real Saroo: 'You have two mothers - lucky boy'. When you have good luck like that you really flourish."

Kidman met Saroo's real adoptive mother Sue Brierley, who lives in Tasmania, as part of her preparation.

"She was more than willing - she flew to Sydney and we spent day together talking and we clicked," Kidman said.

"She's a very gentle, compassionate woman. I got to know her very well."

In its review, The Hollywood Reporter said the Lion was "as enthralling as it is emotional".

The Guardian noted that Lion was likely to strike a chord with many, including Oscar voters.

"It's refreshing to see the complications of a mixed racial identity brought to the screen," it said.

But Variety said that while Garth Davis' film boasted a terrific cast "it's barely meaty enough to wrap the evening news, let alone sustain a two-hour feature".

Dev Patel, meanwhile, was happy to be back at the Toronto festival which he had first attended in 2008, aged 18.

"I rocked up here with Slumdog in my school shoes and a borrowed suit," he recalled.

"It's nice to be back here with a bit of facial hair."

The Toronto International Film Festival runs until 18 September.