Hugh Bonneville shows his dark side in 'I Came By' trailer

Hugh Bonneville looks like he will be taking on quite a different role in Netflix's upcoming thriller I Came By.

The Downton Abbey star will be joined in the film by a cast that includes George MacKay, Kelly Macdonald and Varada Sethu.

In the film, a couple of social activists break into the house of a former high court judge played by Bonneville.

The two activists discover a long kept secret of the judge's that leads him on a dark and dangerous path that will put himself and his family at risk.

Bonneville is best known for playing an array of upper class gentlemen, most notably in Downton Abbey where he has played the Earl of Grantham since 2010.

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He is also known for his role as Mr Brown in the Paddington films and starring alongside George Clooney, Matt Damon and Bill Murray in The Monuments Men.

I Came By is directed by Babak Anvari who is best known for his acclaimed horror-thriller Under the Shadow as well as Netflix's Wounds which starred Dakota Johnson and Armie Hammer.

It will be released in select cinemas on 19 August 19, before dropping on Netflix on 31 August.

Bonneville recently discussed whether he'd return to do more Downton Abbey after the sequel film was released earlier this year.

He said: "I suspect, on a practical level, it's run its course now," he said. "I think that was a good time to quit. I don't know. I'm never gonna second guess the future, but did think for a while, actually, yeah, why not, let's keep going."

Bonneville added: "But I do think it could get a bit thin. I think the second film was such a joyous one and such a good note on which to end the story.

"And it does feel like it can end. There's still open doors in it, but I think it might be the right time to stop."

Watch below: Hugh Bonneville says Downton Abbey has run its course