The city of Charleston, South Carolina is ripped apart by a shooting at a historic church. In the aftermath, the community is divided by the idea of forgiveness.

Stories of loss and heroism during the 2013 shooting at the Washington Navy Yard. The shooter's sister recounts her brother's descent into violence.

Pulse Nightclub in Orlando, Florida is attacked by a shooter who kills 49 people, leaving an entire community devastated and traumatized by the loss.

A shooter's violent path through Santa Monica, California leads to a deadly confrontation on a college campus. An examination of the shooter's mental health.

A white supremacist's deadly attack on a Sikh temple in Oak Creek, Wisconsin and the heroic response by local police, transforms a community.

An exploration of the 1999 attack at a high school in Littleton, Colorado and the myths that may have inspired the active shooter phenomenon. Documentary series finale.