Directors Ricki Stern and Annie Sundberg discuss their HBO documentary, “Marathon: The Patriots Day Bombing” which was produced in association with The Boston Globe. The films offers an intimate look at how an act of terrorism affects individuals and communities long after the act itself. The story is told through three families over the course of the three years that followed the Boston Marathon bombing in 2013.

Premieres November 21 at 8 p.m. on HBO.