After the shooting at Sandy Hook Elementary School in 2012, two parents who lost their children that day—Nicole Hockley and Mark Barden—founded Sandy Hook Promise, a nonprofit devoted to protecting kids from guns by teaching people to recognize the warning signs of potential violence before it occurs. This week on Tagline, we look at the the group's remarkable PSAs over the past decade—created with BBDO New York and the Smuggler director Henry-Alex Rubin—and how the bravery, boldness and craf...