Donnie Darko helmer Kelly will write and direct the film, which will feature Cage as real-life lawyer and scholar Rodney Smolla, Variety reports.
Smolla was called upon to defend a publishing company after a class-action lawsuit was brought against it by the families of several murder victims.
A book published by the company - Hit Man: A Technical Manual for Independent Contractors - was used by contract killer James Perry during his preparations for the multiple homicide, which he was hired to carry out by Motown Records exec Lawrence Horn.
The victims were Horn's wife, his quadriplegic son and his family's overnight nurse, whose deaths Horn orchestrated in the hopes of securing his son's $2 million trust.
Kelly's next project was, until recently, planned to be Edgar Ramirez-starring drama Corpus Christi, but the film remains in the development phase.
Cage has also been cast in upcoming William Friedkin thriller I Am Wrath, and is rumoured to be in talks to join The Expendables 3.
Watch a trailer for Donnie Darko below: