"My brother @austinkingsleyswift just acted in his first movie and I'm all proud and stuff," she posted in September, along with a shot of Austin mid-scene.
The film centers on an I.T. consultant-turned-hacker (James Frecheville) who turns a wealthy businessman's (Brosnan) life upside down when their relationship runs sour, stalking his daughter and threatening his family, business, and life.
While details of Austin's role are still unknown, he can be seen in the trailer around the 1:30 mark.
Watch the trailer below.
I.T. is set to hit theaters and video on demand on Sept. 23.