Tension and violence amid beautiful scenery

We open in a prologue of quiet, picturesque scenery, upended by the tension of our main character, Milton, waiting and stalking his targets before assassinating them and a police officer who stumbled upon the scene. But at the last moment, Milton cannot kill his targets' child, and we see a glimmer of humanity in him. I am left wondering who is Milton and is he a good guy or a bad guy??