Horror on the Hook

From publisher blurb:

This one-shot adventure is about a series of attacks that happen in a large city. A strange kind of creature creeps up from the sewers and attacks the unwary. It takes the bodies but sometimes a mangled corpse is left behind. The horrendous monsters are described by the few survivors as a strange, dark, feathered abomination with hooks instead of wings (hook horror). They feathered horrors have adopted a cave next to the sewers as their new lair and do their best to protect their nests and eggs.