Is there weed or a weed equivalent in your setting?

>>54908849
Opium.

Yup. There was a plothook where southern traders were illegally transporting cannabis across the border of a neighboring country without paying the tax. Government sent out enforcers to seize any illegally transported goods, but that just forced the traders to take more treacherous routes. A bunch of the traders went totally missing and the party was sent out to figure out why.

It was a witch.