An Act of Dog tells the story of Mark Barone, an artist who sets out to paint 5,500 portraits of dogs after his partner Marina Dervan discovers that's the number of dogs killed every day in our nation's shelters. When Marina shows him the evidence, he doesn't want to look, but it's the pure raw number that drives him to pick up his brush in an effort to change the status quo. After thousands of paintings begin to take their toll on him, Marina wonders if Mark can make it to the finish line.