The entertainment publication reports De Niro is in negotiations to play an operative orchestrating a corporate coverup related to the death of the daughter of Gibson's lead character.
Gibson is set to play a Boston police detective whose investigation causes him to become embroiled in the corporate and government conspiracy.
The Martin Campbell-directed film will mark the first time Gibson has served as a film's lead character since the 2002 films "Signs" and "We Were Soldiers."
Variety said "Darkness" has been adapted for the big screen by William Monahan, who was working from a 1985 BBC mini-series.
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