The apothecary’s errand

An original fiction passage set in the nineteenth century.

Mr Hale wrapped the small bottle in paper and secured it with string. “You must carry this to Blackthorn Farm before nightfall,” he told his assistant. The colour drained from Elias’s face. Everyone in the town had heard rumours about the lonely farmhouse. Then he mastered himself, tucked the medicine inside his coat and said that he knew the quickest road.

Identify the phrase which reveals Elias’s momentary dread of the errand.