Sins of the past

To the kingdom, he is a legendary hero. To the dead, he is the man who stole their tomorrow.
Once a celebrated commander who led the King's men into "righteous battle," an aging soldier now lives out his final winters in absolute isolation. The glory of the crown has faded, leaving behind only a rusting sword upon the mantelpiece and a crushing weight of guilt. He is haunted not by his enemies, but by the faces of the young lads and old men he cut down in the mud-actions once hailed as valor, but now recognized as atrocities.
But the battlefield has followed him home.
Every night, he is trapped in a terrifying limbo. Frozen in his bed and unable to scream, he is forced to watch a silent, unnatural entity with hollow, pearly eyes slowly creep from the windowsill toward his throat. To survive the daylight, he abuses his senses-clinging to the bitter burn of a short black pipe and the taste of ruined, charred meat just to shock his mind away from the whispering dark.
Too proud to yield and too terrified of the madhouse to seek help, the old warrior faces his final, most brutal campaign entirely alone. As his strength fails and his mind unravels, he must confront the ultimate question: Is the creature in the shadows a demon of the night, or is it the vanguard of death itself, coming to collect the debt of his sins?