Philadelphia, 1965: Two street cops—one black, one white—are gunned down in a corner bar. One of the fallen officers, Stan Walczak, leaves behind a 12-year-old boy, Jimmy.

Philadelphia, 1995: Homicide detective Jim Walczak learns that his father’s alleged killer, Terrill Lee Stanton, has been sprung from prison. Jim stalks the ex-con, hoping to finally learn the truth.

Philadelphia, 2015: Jim’s daughter Audrey, a forensic science student, re-opens her grandfather’s murder for a research paper. But as Audrey digs deeper, she comes to realize that Stanton probably didn’t pull the trigger—and her father may have made a horrible mistake…