Night Blade

From publisher blurb:

The city streets of Otrista are a playground to shadows and all that hide within them. Nothing is sacred on these cobbled streets, not even priests who must walk them. A worshiper of Matalik, the ‘Ashen Curse’, fell victim to these shadows, and now finds sport in this abyssal filth as retribution. He releases a vengeful slayer, one who is uncaring and unwavering in its purpose to spill blood, regardless of whom it encounters.

Night Blade is a combat encounter, ranging from 'medium' to 'hard' in difficulty for four to six players and is scalable, starting at 2nd level.