Red Light Winter premiered at the Steppenwolf Theatre in an extended run and later arrived Off-Broadway, with its original Chicago cast, for another extended engagement at the Barrow Street Theatre in 2006.
Rapp, who also helmed the stage production, will direct the film. Mark Ruffalo and Billy Crudup were at one time attached to the film, but are no longer involved. Foster ("Contraband") replaces Ruffalo; no casting for Crudup's role has been announced.
In the play, "former college buddies Matt and Davis take off to the Netherlands and find themselves thrown into a bizarre love triangle with a beautiful, young prostitute named Christina. The romance they find in Europe is eventually overshadowed with the truth they discover at home."
Dunst will portray Christina, with Waterston cast as a woman who shares a past with both men.
The film is produced by Jay Van Hoy and Lars Knudsen, as well as Scott Rudin, who was also among the play's original producers.
Rapp's plays include Hallway Trilogy, Ghosts in the Cottonwoods, The Metal Children, Nocturne, Faster, Animals & Plants, Finer Noble Gases, Stone Cold Dead Serious, Blackbird, Gompers and Essential Self-Defense.