One Perfect Witness

On a remote Scottish hillside, three paths meet.
On each path, a boy, one carrying a gun.
When their paths cross, a shot is fired and a boy dies.
That leaves two - one killer and one perfect witness.
This killer will stop at nothing to make sure the witness says nothing. Difficult for most people, even for someone who’s been guarding a secret of his own for five years.
What if the witness decides he’s been silent too long?
Sometimes even the unspeakable must be spoken if we can find the words.