The film's script has been adapted from the action novel of the same name, which is part of Vince Flynn's series of Mitch Rapp books, reported Variety.
It sees Rapp join the CIA after his girlfriend is killed in a terrorist attack and work under the guidance of an experienced operative.
Willis, 57, has been in talks about playing the mentor for some time and now looks set to sign up.
This film will see Willis pair up with producer Lorenzo di Bonaventura again.
They have worked together on the hit action-comedy "Red" in 2010 and have both already signed up for the sequel, which will go into production later this year.
Willis will also be seen in action alongside Joseph Gordon-Levitt and Emily Blunt in "Looper", which hits theatres on September 28.