This 9/11 hero’s legacy is larger than the big screen. The sons of an NYPD detective who was killed when he courageously charged into the World Trade Center on Sept. 11, 2001 are following in their father’s large footsteps — and a new movie documents their call to serve.

Opening in select theatres on Friday, “Twin Towers: Legacy” follows the story of the Vigiano men, who have continued the family’s tradition as first responders after losing their father, Joseph, and his firefighter brother, John, in the terror attacks 24 years ago. “I’m very proud of my boys. They are trying to make the world a better, safer place,” Joseph’s widow Kathy Vigiano told The Post in a recent interview.