Naomie Harris says she struggled to switch off whilst filming Mandela: Long Walk To Freedom.
Harris is back on the big screen this week as she plays Winnie Mandela in the biopic film.
And the actress says because she had to go to some dark places for this role it was hard to switch off and leave the character behind.
Speaking to Red Magazine, the actress said: ""It meant inhabiting places I try never to go, like revenge, hatred and rage.
"I don't hate anyone, and I'm really not a vengeful person, but I found it really difficult to switch off.
"Even after I stopped filming, it took me a while to shake her."
The movie sees Harris star alongside Idris Elba for the first time, as he takes on the role of Nelson Mandela.
However, it did give her the chance to work with director Justin Chadwick for a second time: the pair first worked together on The First Grader.
Mandela: Long Walk To Freedom is the first big screen outing for Harris since the huge success of Skyfall in 2012.
Mandela: Long Walk To Freedom is out now.
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