As we approach the four-year anniversary of the mass shooting at Sandy Hook Elementary School, a new gun violence PSA is urging viewers to open their eyes to the early warning signs of potentially dangerous behavior.

After their 6-year-old sons were killed in the shooting, Newtown parents Nicole Hockley and Mark Barden teamed up with other victims’ loved ones and community members to create Sandy Hook Promise ― a nonprofit that works to protect children from gun violence.

Today, the organization released a new PSA in conjunction with their national “Know the Signs” campaign. Titled “Evan,” the video offers a glimpse into the lives of high school students. While a dark ending is somewhat expected, the video’s twist takes a surprising direction.

“The PSA demonstrates how easy it is for one to overlook the signs of an at-risk individual demonstrating signs of violence, particularly gun violence, and that when one knows the signs, it can be prevented,” a Sandy Hook Promise representative told The Huffington Post in an email.