Filmmaker Spike Lee (“Chi-Raq”) was a familiar face at Steppenwolf Theatre in September for what has turned out to be a secret film project.

Lee came to town to film Antoinette Nwandu’s “Pass Over,” a spokeswoman for Steppenwolf confirmed Tuesday. The film project is a joint effort by Lee and Amazon Studios (which also distributed “Chi-Raq”).

According to the spokeswoman, Lee acquired the script after the world premiere run at Steppenwolf had ended in July and he and the studio approached the Chicago theater company about making the film. The production staff at the theater rebuilt the show’s set in the theater’s downstairs stage in one week. The film was subsequently shot over one weekend, with an invitation-only guest list, coordinated by Lee and Father Michael Pfleger of St. Sabina Church. All parties were apparently sworn to secrecy.

While the filming featured the original stage cast of Julian Parker, Jon Michael Hill and Ryan Hallahan (in the dual roles of “Mister” and “Police Officer”), the movie version features Blake DeLong in the role of the cop. The play was directed by Danya Taymor.

The film will be an official “special event” selection at the Sundance Film Festival in January, the festival announced Tuesday.

The play became an international topic of controversy when objections were raised to some of the commentary in a review by Sun-Times theater critic Hedy Weiss.